Home » Horticulture » Beans

Beans

By in Horticulture on .

Beans (Phaseolus spp.) are a leguminous agricultural crop.

Due to some confusion about trivial crop names on this page, the term “bean” refers to species of the genus Phaseolus spp, primarily the common bean (Phaseolus vulgaris). Another species, also often called “bean” is described on the page “Forage beans” (Vicia faba).

 
Common bean (Phaseolus vulgaris)
Common bean (Phaseolus vulgaris)
Source: flickr.com
©Carl Lewis (CC BY 2.0)

Horticulture

Navigation

Horticulture

Economic importance

Bean seeds and green beans are used for food purposes fresh, boiled and canned. The seeds contain 21-30% protein with good taste (comparable to peas), 1.6% fat, 40% carbohydrates, 4.0% minerals. To reduce cooking time, bean seeds are pre-soaked before boiling or pressure cooking and eaten either as soup, mashed potatoes, or just plain, without broth. Like most legumes, they contain few sulfurous amino acids, such as methionine, so they are consumed with other vegetables or cereals, such as rice, to ensure a complete diet.

Green beans contain up to 15.7% protein in terms of dry matter, up to 2% of crude sugars, and up to 22 mg/100 g of vitamin C. The protein quality of green beans is good, although the level of sulfur-containing amino acids is low. The caloric value of dried bean seeds is very high – 336 calories per 100 g.

Although green beans do not provide as much protein and calories as dry bean seeds, they are nevertheless an important source of protein, vitamins, and minerals. In addition to eating cooked bean pods, it is common in many parts of Africa and Latin America to eat the shoots and leaves as greens. Hard, coarse but immature seeds (the beans in their shells) and, to a lesser extent, the dried seeds of some bean varieties are also consumed.

Most bean varieties have been selected or bred for specialized markets, and consumers tend to prefer certain varieties. Therefore, there is a very wide range of characteristics, particularly seed size and color, available as varieties for these specific requirements. Most dried beans are rehydrated and cooked either whole or as bean flour or grits. Dried seeds can be successfully stored and are therefore a valuable source of protein in human diets in developing countries. They can be easily transported and industrially processed.

Dried beans have many uses, but as a processed crop, white sea beans are probably best known as canned baked beans, which are sold in the United States, Canada, and the United Kingdom, with production reaching 4 million cans. The beans are soaked and then cooked under pressure in a can of tomato sauce (a mixture of cornmeal, spices and tomato puree).  Large quantities of white dried beans are canned in tomato sauce and sold as baked beans in the United States, Canada, and the United Kingdom, and colored beans are canned or processed to make bean salads or ready meals.

Attempts have been made to develop the cultivation of sea beans as an agricultural crop in the United Kingdom. The main limiting factor in this development is the short growing season and the risk of adverse weather conditions negatively affecting completion of maturation and subsequent harvesting. The suitability of growing areas is also limited by the fact that beans do not tolerate low temperatures well. Work has been done to develop varieties with earlier maturity that are more likely to be successful and that also have resistance to seed-borne bacterial diseases such as halo blast. However, the economics of production have been such that relatively low yields, uncertain success and lack of investment in specialized harvesting equipment, as well as demand from processors for large volumes of beans that must be available for processing year-round, have not contributed to any significant level of production in the UK. In contrast, several other Phaseolus bean species, especially those with colored seeds, have been bred and are grown in the UK on a small scale (Leakey, 1999).

Seed color is not important when the pods are consumed fresh, but varieties with white seeds are preferred for canning because the dark seed shells discolor the canning liquid. Although varieties with white seeds are preferred, dark varieties are also used for freezing.

Other bean varieties, especially dark red and large butter beans, are canned in brine. Other processes include rehydrating and freezing to make mixed bean salad. For home consumption, beans are soaked and cooked either in a mixed stew or strained and separated for use as dal.

Multiflower beans also find use for ornamental purposes. Some forms of beans are suitable as green fertilizer. From an agronomic point of view, the bean is a valuable crop. Stubble root residues accumulate up to 101 kg/ha of nitrogen, up to 33.8 kg/ha of phosphorus and up to 135 kg/ha of potassium. During the growing season, plants are not damaged by pests, and therefore the bean can be considered a sanitary crop in the crop rotation. All this makes it one of the best preceding crops.

Because of the presence of trypsin inhibitors in beans, they are not suitable for animal feed, and for human consumption they must be boiled before consumption.

The green mass of Asian bean species, such as mung bean and adzuki, is suitable for fodder purposes. The green mass of common bean is not eaten by animals. Grain and green plants contain poisonous glucoside fazsolunatine, which leads to poisoning of animals, causes suppression of growth and hypertrophy of the pancreas. Thermal treatment destroys the poisonous substances.

Bean leaves are used to produce citric acid.

It has the ability to nitrogen fixation.

History of the crop

P. vulgaris was previously thought to have originated in Asia, but it was later proven that the bean was first domesticated in the New World: archaeological remains were found first in Peru and then in the southwestern United States. Since then, several more remains have been discovered in the Andes, Central America and North America.

Vavilov proposed southern Mexico and warm regions of Guatemala as the primary center of origin and Peru, Ecuador and Bolivia as secondary centers. According to other data, the common bean and its numerous biotypes originated from the wild P. aborigineus in the Andean regions. According to another theory, the common bean was domesticated in South America and transferred to Central America, where the maximum diversity is observed. However, Singh et al. (1991) pointed to two different gene pools of common beans, one of Andean origin and one of Mesoamerican origin (Central America and Mexico). Most bean varieties appear to be of Andean origin with introgression from the Mesoamerican group.

Radiocarbon dating has determined that the common bean originated more than 7,000 years ago. European explorers were responsible for the early export of Phaseolus species from the New World, especially P. vulgaris, to other parts of the world, where they were well adapted and quickly adopted. In the wild, the common bean is found from low to high altitudes and from dry to wet environments. However, species with fleshy pods (snap) appear to be less adaptable to the climate than those with dry pods.

Domestication has resulted in less branching while the number of flowers, pods, and seed size has increased. Although seed size increased, the number of seeds per pod decreased. Overall, pod dehiscence and pod fiber development decreased and pod fleshiness increased compared to bean varieties. Dry seed water permeability increased and seed hardness decreased. In many biotypes, there was a shift from short-day photoperiod response to day-length neutrality. Although wild species of Phaseolus have perennial and annual forms, most modern vegetable Phaseolus are annual.

Since ancient times beans have been cultivated in South and Central America. At the end of the 16th century, the bean was introduced into Europe, and in the 17th and 18th centuries it began to spread in Russia.

The small-seed bean or mung bean was introduced into cultivation 5-6 thousand years ago in South Asia (India, China, Japan).

Cultivation areas and yields

Most of this crop is now grown worldwide for dry seeds, a smaller portion is also grown as a vegetable, where the pods are harvested and consumed fresh or preserved as a frozen product. With these different forms of the final product, there is a huge variety of seed and pod characteristics in shape, size and color, which has led to the creation and commercial cultivation of a wide range of varieties. Some varieties still retain their whorl characteristics, but many have been bred as short, upright bush plants.

In world agriculture, the area planted with beans is second only to soybeans among leguminous crops. Global cultivated area is approximately 24-28 million hectares, or 17% of the total legume crop area. The gross seed yield is 18 million tons or 8% of the gross legume seed yield. The average yield is 0.7 t/ha.

Currently, dry seed is grown in many subtropical and more temperate regions, but the most important regions are South and Central America and Africa and West Asia with 11 million hectares planted, of which 6 million hectares are in India, Europe and the United States. According to FAO statistics, Brazil and Argentina, Mexico, India, China and Myanmar (Burma), the United States and Canada produce the most beans, with total global production of more than 23 million tons per year.

Green (string) beans are an important crop in developed countries and are grown on a large commercial scale in Europe and the United States. A wide variety of varieties are available, often characterized by pod length, width, and color. Although most commercially grown varieties have green pods, there are color variations ranging from dark green to yellow; varieties with yellow pods are known as wax beans. In addition, pod shapes can range from round (Blue Lake varieties) to flat (Romano varieties).

Asia and Europe, with more than 50% and 33% of world production, respectively, are the dominant producers of string beans. China and Turkey are the leading individual countries, each with more than 17% and 13% of world production, respectively. Production data from many small farms and homesteads are not reported, so accurate collection of production statistics is not ideal. Also, the widespread practice of intercropping beans with other crops makes data collection difficult.

In the USSR, the area of bean crops was approximately 53 thousand hectares. Among the countries of the former USSR, the main sowings were concentrated in Moldova, Ukraine, Georgia, and Belarus. In Russia, there are no official statistics on the area and yield of beans; it is supposed that by the end of XX century, the area under beans was 10 thousand hectares, the gross yield was 14 thousand tons, and the average yield was 1.4 t/ha. In Russia main regions of cultivation are North Caucasus, Far East, Central Black Earth zone, Non-Black Earth zone, Siberia. It is also cultivated on homesteads in most regions. Early varieties can be cultivated as far as St. Petersburg.

Seed yields range from 1 to 3 t/ha depending on soil and climatic conditions. In the Krasnodar region yield reaches 2.5-2.8 t/ha. The maximum possible yield is 3.5 t/ha.

Chemical composition and nutritional value

Typical nutritional value of green beans (data from the British Growers Association and U.S. Department of Agriculture Standard Reference SR27), per 100 grams of product:

  • caloric value – 130 kJ;
  • protein – 1.8 g;
  • total carbohydrates – 7.1 g (1.4 g as sugars);
  • dietary fiber – 3,4 g;
  • sodium – 6 mg;
  • vitamin C – 16.3 mg.

Nutritional value of dried beans (USDA Standard Reference SR21 data), per 100 g of product in boiled form:

  • caloric value – 494 kJ;
  • protein – 8,3 g;
  • total carbohydrates – 21.1 g (2 g as sugars);
  • dietary fiber – 7,0 g;
  • sodium – 2,0 mg;
  • iron – 2.1 mg;
  • folate – 102 mg.

Botanical description

The genus Phaseolus includes about 55 species (Debouk, 1991), all of them of American origin. This number includes several cultivated species cultivated for their fleshy pods, immature and mature seeds.

By origin and botanical traits, beans are divided into American beans and Asian beans. The American bean includes the species:

  • common bean (Phaseolus vulgaris);
  • multifloral beans (Phaseolus multiflorus);
  • spiky bean, or tepari (Phaseolus acutifolius var. latifolius);
  • lima beans (Phaseolus lunatus).

In America, the fiery red bean (Phaseolus coccineus) is also economically important.

Asiatic beans include the golden bean or mung bean (Phaseolus aureus).

There are husked and sugar (asparagus) varieties by the structure of their seeds.

In Russia, the common bean (Phaseolus vulgaris) is cultivated mainly.

Previously, several species of legumes were classified as members of the genus Phaseolus, but now they are attributed to the genus Vigna: among the reclassified species are the moth, adzuki, mung, rice and urd beans.

Green beans are often called dwarf, French or snap beans, respectively in green, dwarf, French or snap beans. They can be divided into groups according to their maturity at the time of harvest. Green, French or snap beans are grown as a garden crop and harvested fresh; they are consumed as pods, fresh or processed.

Common bean (Phaseolus vulgaris)

The common bean (Phaseolus vulgaris L., syn. Phaseolus vulgaris Savi) belongs to the genus Phaseolus, legume family (Leginnenosae).

It is represented by bush (dwarf determinate), semi-twisted and climbing (indeterminate) forms. Modern determinant bush varieties differ from the earlier indeterminant climbing varieties by less apical dominance and little or no response to short day photoperiod. The non-determinant curly and upright varieties branch more and, because they have more flower-bearing nodes, have greater yield potential.

Common bean is a warm-season annual with a herbaceous stem, woody at the base. Shrub forms reach a height of 25-60 cm with few nodes and apical inflorescences. Climbing forms can reach a length of 2-3 m and have up to 25 flower nodes. Curly forms are very lazy, so they are usually supported on poles or trellises.

The root system is taprooted. The root system of many bean varieties is usually small and not extensive, and the lateral ramifications are shallow. The main root is usually short, but can reach about 1 m in deep, loose soils. In the presence of Rhizobium bacteria, the lateral roots develop nodules. A root system that firmly anchors the plant is an important characteristic for mechanized harvesting.

Leaves are pinnatipartite (ternate), often pubescent. The shape ranges from rhombic to broadly ovate. Modern varieties have small leaves, which improve light penetration under the canopy, especially at high crop densities. Although this characteristic tends to increase the overall yield, the small leaf size is associated with small bean size. Leaf color varies from yellow-green to blue-green.

The inflorescence is a brush with 2-8 flowers, located in the axils of the leaves. The flower is large, perfect, moth-like, white, pink or purple. 10 stamens, 9 of which are united in a tube enclosing a long ovary; one upper stamen is free from the rest. The bean is a self-pollinating plant, sometimes cross-pollination by insects is noted.

The fruit is a 3-10-seeded pod. The number of seeds is one of the characteristics of a variety; most bean varieties contain three to five seeds. Depending on the variety, the bean can have a variety of shapes, from straight to saber-shaped, with a straight or curved spout. The bean is almost always significantly longer than the bean is wide; the length varies from 8 to 20 cm or more, and the width varies from less than 1 to several cm. The color of immature beans is yellow, green, but in some varieties (borlotti beans, also known as cranberry beans) may be white with contrasting marbled-red spots on the surface. Other species or varieties may be purple or nearly black. In mature beans grown for dry picking, such as sea beans, the color of the pod is usually tan. Depending on the variety, the cross-sectional shape varies from round to elongated-oval, and some are heart-shaped.

The number of pod fibers and the rate at which they develop also vary. Through breeding, the amount of fiber has been greatly reduced. The beanless variety was bred more than 100 years ago. Nowadays, only reproductive and other older bean varieties have strong, string-like string fiber. Calvin Keeney, a seed grower from LeRoy, N.Y., is credited as the author of the first beanless variety, bred around 1800. Linelessness is a recessive trait and is present in most varieties grown today. Threadless varieties also contain fewer wall fibers. The word “thread” was used because of the strong string-like fibers at the dorsal and ventral joints of the pod, the dorsal being the strongest. When the seeds were fully mature, the pod would burst. The term “snap” probably originated from the sound made when fresh pods were cracked. Most common bean pods are bare, some have pubescence. The pods do not have a strong calyx like the pea.

The beans are attached to the stem low and do not ripen simultaneously, which makes harvesting very difficult.

The size and weight of mature seeds varies greatly: seed length varies from 5 to 20 mm, and the weight of individual seeds of some varieties ranges from 0.15 to more than 0.80 g. Seeds are round, rounded, ovoid, oblong, and kidney-shaped. The color of the seed coat depends on the variety and can be many colors and combinations, which is of some importance. Interestingly, different countries in Latin America prefer a certain color of seed coat: black coat – Brazil, El Salvador, Mexico and Venezuela; red – Colombia and Honduras; yellow – Peru; white – Chile. Varieties grown for processing usually have white or light-colored seeds. Other important characteristics of mature seeds are seed coat thickness and stickiness and cotyledon resistance to cracking; resistance to cracking is genetically related to seed coat color.

According to usage, the common bean (Phaseolus vulgaris) is divided into the following groups:

  • French beans: green, yellow or purple fleshy pods containing underdeveloped seeds are eaten. The pods have no filament or parchment layer.
  • Haricot filet bean: The pods contain threads, but the fleshy immature pods are edible.
  • Haricot: The fresh seeds are edible; the pods contain threads and fiber and are not usually eaten.
  • Dry (field) beans: dry husked seeds are eaten, pods contain threads, fiber, a strong parchment layer, and are not eaten.

In domestic practice, bean varieties are divided into vegetable (asparagus, string beans) and grain varieties (peeling) depending on the presence of a parchment layer and fibers in the bean flaps. Vegetable varieties have fleshy beans due to the strong development of the parenchyma and weak development of the parchment layer. In addition, the sclerenchyma of the vascular-fiber bundles is not developed in some of them. Therefore, the beans of asparagus varieties are tender and are edible until the seeds are formed. The beans of these varieties do not crack, but are poorly threshed.

In peeling varieties, the parchment layer develops early and may be as thick as 1/10 to 1/20 of the bean leaf thickness. Therefore, they are not used for eating green beans. The presence of the parchment layer is determined by breaking the bean, and to determine the presence of fiber, tear off the tip of the bean. If a thread is pulled along the seam of the bean, then fiber is present.

The seeds are differently colored, sometimes mosaic. Weight of 1000 seeds is 200-500 g. 

Multifloral beans (Phaseolus multiflorus)

Multifloral beans (Phaseolus multiflorus Wild). Has a long curly stem, large white and red flowers, large flattened elliptical seeds. Weight of 1,000 seeds 700-1200 g. Beans are short, wide with a beak. The bean sprouts do not bring seeds to the soil surface. In Russia it came under the name of ‘Turkish beans’ in the 18th century.

 

Sharp-leaved beans (Phaseolus acutifolius)

Sharp-leaved or tepari beans (Phaseolus acutifolius Agrad). It occurs in bush forms. The pods are flat, short with a beak, and the seeds are small. Weight of 1,000 seeds 100-140 g. Leaves petiolate, pointed. Inflorescence is brush-shaped with a short pedicel. Drought-resistant. This species was known to ancient Indians.

 

Lima bean (Phaseolus lunatus)

Lima bean, or moon-shaped bean (Phaseolus lunatus L.). Suitable for food purposes. The flowers are small. Beans are wide, short, and flat (semilunar), consisting of 2-3 seeds, easily cracked. Seeds are kidney-shaped and of various colors. Weight of 1,000 seeds 250-1,000 g. Cultivated in America, Africa, Asia and some European countries. In Russia it is found in kitchen gardens.

 

Golden beans (Phaseolus aureus)

Golden beans or mung bean (Phaseolus aureus Piper). A creeping or semi-creeping pubescent plant. Has long narrow, narrow, multi-seeded, beakless beans. The seeds are small, yellow or green in color, and weigh 1,000-30 g. In Central Asia and Transcaucasia, it is used for food; straw is used for fodder. It is more demanding of heat and moisture than the common bean. Cultivated in Asia, small areas are available in the Far East of Russia.

 

Physiology

Germination

Seed germination of common bean and other species is epigeic as the seed buds emerge from the soil along with the shoot. The first germ leaves develop from the shoot as one pair of opposite and (usually) ovate leaves. The germinal remnant then shrivels up and falls away from the stem, leaving two small scars. The shoot continues to develop, forming pinnate and mostly three-lobed true leaves.

Vegetative development

The stem continues to elongate, more leaves appear on the lateral axes, which may vary in length, and some branching may occur. The stems are round in cross section, and the lower part of the stem is usually erect without twisting, while the upper part of the stem may begin to twist, as in some curly species around a support. However, the more determinate bean species tend to remain upright and develop as bushy forms.

The leaves develop oppositely and alternately up the stem, but buds develop in the leaf axils, which in turn produce secondary leaf branches. The leaves are three-lobed, with the two lateral leaflets asymmetrical and the terminal leaflet symmetrical.

Two distinctly different types of growth can be distinguished among bean varieties: determinant and indeterminant. The difference is that in the first, the main stem and side branches end in inflorescences, while in the second, the main stem and side branches are topped with a vegetative meristem that can continue to grow and develop more leaves and flowers. In these indeterminant varieties, the flowers are located laterally, directly at the nodes of the main stem and side branches.

Determinant types have been described according to two main characteristics: those with few nodes and those with many nodes. Species with few nodes have three to seven three-leaflets on the main stem before the terminal double inflorescence; they have been selected for early maturity and are more suitable for cultivation in cool temperate climates. Multiple-row species include those with 15-25 leaves on the main stem. In determinate species, the plant is almost always erect because of the short internodes, while indeterminate species often have the ability to climb because of the long internodes. In these latter types, some species have abundant branching and are prostrate, while others have reduced branching and are often grown with maize in the high Andes (Debouck, 1991).

Root development

The root system of the bean consists of a thin branching system that is relatively shallowly developed. Multiple branching of adventitious roots occurs in unconsolidated soil conditions. In the presence of a population of Rhizobium bacteria, nodule development occurs mainly in clusters around the main root, but nodules can develop on any part of the root system and its branches.

While beans benefit from a symbiotic relationship with soil Rhizobium to fix nitrogen, plants grown in non-native regions of the world, especially in Europe, North America and Australia, where there are no natural populations of certain Rhizobium strains, require additional sources of organic or inorganic nitrogen. Some crops are grown using commercial formulations of Rhizobium inoculant applied either to seeds before planting or as pellets in the soil, but this is often less effective and additional nitrogen is often required.

 

Flower development

Flowers form from axillary buds at the nodes of the main stem. These lateral branches or peduncles may produce several groups of up to three flower buds on bracts located on one or more peduncles. Flowers are typical of legumes (Fabaceae). Several flowers form on the axillary bud, which may end in a terminal inflorescence.

 

Pod development

Pod setting occurs acropetrically from the base upward, but flowers can fall off and this can occur on any of the inflorescences, and up to 50% loss of flowers is noted during flowering and pod setting. Environmental conditions may affect flower persistence, but the full list of causes is unclear.

Although insect pollinators assist in the pollination of P. vulgaris, many flowers are self-fertile. After pollination, pods form, which botanically are dehiscent fruits, each side of the pod being a carpel. In the natural state, the pods open at the seams to release the seeds.

 

Biological features

Temperature requirements

Common bean is a thermophilic plant. The minimum temperature for bean seeds to germinate is +8 … +12 °C, sprouts appear at 12-13 °C. At temperatures below +8-10°C germination slows down, and many seeds rot. Temperatures above 35°C also do not contribute to germination. The optimum temperature for seed germination is 25 to 30°C. Under good conditions, germination occurs within 7 to 12 days.

Influence of temperature on common bean germination (National Garden Bureau, Inc. Downers Grove, IL.):

  • at 10 °C there was no germination;
  • at 15 °C germination occurred after 16.1 days;
  • at 20 °C it took 11.4 days;
  • at 25 °C it took 8,1 days;
  • at 30 °C after 6.4 days;
  • at 35 °C we had germination after 6.2 days;
  • no germination at 40 °C.

Effect of temperature on germination of lima beans (National Garden Bureau, Inc. Downers Grove, IL.):

  • at 10 °C there was no germination;
  • at 15 °C germination occurred after 30.5 days;
  • at 20 °C it took 17.4 days;
  • at 25 °C it took 6.5 days;
  • at 30 °C we had germination after 6.7 days;
  • no germination at temperatures above 35°C.

Frosts as low as -0.1 … -1°C are detrimental to seedlings; according to other reports, short-term frosts of -0.5 … -1.5°C are detrimental to seedlings. Growing sprouts can withstand slight frosts.

Some varieties (usually dark-coloured ones) may germinate at 7-8°C, and some varieties survive night frosts as low as -2°C.

During sprouting phase, beans do not tolerate even short-term frosts and die at -0,5-1,5 °C; during flowering phase, beans are damaged at -0,5-1,0 °C, during ripening – at -2,0 °C. The temperature of 0 … +5 °C causes disturbance of physiological processes, delays in growth and development, prolonging vegetation period by 10-27 days and reducing productivity by 10-70%.

An average temperature of 20-25°C is optimal for growth and high yields. Field beans grow better at lower temperatures and are more sensitive to high temperatures during flowering than bush varieties. Heat stress has a negative effect on pod set, and some varieties are more resistant to it than others. A favorable soil temperature range is 18-30°C.

During budding and flowering, beans are sensitive to high temperatures. At nighttime temperatures from +17°C to +27°C or daytime temperatures from +22°C to +32°C, the formation of buds stops, and buds, flowers, and ovaries to 3 cm fall off. Ovaries larger than 3 cm suspend growth and wither under the influence of high night temperatures. This is noted in both drought and continuous irrigation and fog spraying.

Beans develop and grow normally at an average daily air temperature of at least +15 ° C. The optimal temperature for growth and development depending on the phase of bean development is in the range +18 … +30 ° C. 

Golden bean (mung bean) is the most temperature-demanding form. Heat-tolerant.

Moisture requirements

The bean is considered a less water-intensive legume than the pea, lentil, or fodder bean. However, beans need moisture during the germination period.

Seeds need 104.5% (100-120%) of their weight of water to swell. There is also a greater need for water during the flowering and setting phases of the beans. Soil moisture during this period should not be less than capillary rupture moisture.

Beans are sensitive to drought and flooding. Ideally, moisture should be evenly distributed throughout the growth period; 250-450 mm is usually sufficient. Proper moisture management is essential for high yields. Soil moisture should be close to the field capacity, especially during flowering. According to other recommendations, the optimum soil moisture for beans is 50-85% of the full moisture capacity, depending on soil and climatic conditions, the phase of plant development, fertilization, and biological characteristics of the variety.

After sprouting, the bean tolerates short-term drought until the phase of budding. However, excessive air dryness causes leaf wilting. Under conditions of severe prolonged drought, the bean plants remain viable, but there is a significant decrease in productivity. Under a water deficit, the bean plants have a break in flowering and growth processes are suspended. After normalization of water conditions, flowering and filling of beans resume, but the lag in plant development is not compensated.

During the phase of budding, flowering and bean formation, beans are especially sensitive to lack of moisture. If drought occurs during this period, wilting of leaves, a reduction in bean quality (thickening of the parchment layer in the pods), and loss of buds, flowers and young beans may also occur. Vegetable beans are more water-loving than grain beans, so even in hot weather, yields are significantly reduced.

Drought leads to a decrease in biomass, seed and pod yield, number and size of seeds, and impairs color, fiber, and firmness. When drought occurs, ripening occurs as in normal moisture, but may be shortened by 1-6 days. The average seed yield is reduced by 27-62%.

Dry winds can cause flower drop.

Excess moisture and flooding causes anoxia, to which beans are very sensitive, and leads to an increased incidence of root rot.

Light requirements

The bean is a light-loving plant. Most modern bean varieties are insensitive to photoperiod. Nevertheless, some varieties that develop flower buds only on short days are still used.

The crop is especially sensitive to light when it is young, less so during the flowering phase. In strong shading, its sprouts stretch and weaken, which negatively affects the formation of yields.

The light phase of spring development is accompanied by a short daylight period, but there are some varieties which respond positively to day length. These are mostly varieties cultivated in northern latitudes. With short daylight hours, beans accelerate their development and shorten their growth, which manifests itself in a decrease in plant height and other economically valuable traits.

Beans realize their need for light by their ability to change the angle of their leaves in relation to the sun’s rays. This ability increases the efficiency of photosynthesis and is also used to prevent plant overheating and excessive transpiration, but weakens the crop’s ability to resist weeds. Bean leaves face and follow the sun, but during periods of excessive heat and low soil moisture, the leaves turn parallel to the sun’s rays.

Yields are reduced when plants are shaded.

Soil requirements

Optimal soils for growing beans are light chernozem, sod-podzolic, sandy loam, light loam, loamy fertile soils, rich in lime, structural (medium-structured), medium-consolid, not too moist, well-drained, loose.

Optimal agrochemical indicators of the arable layer for beans:

  • pH 6.5-7.5 (pHKCl – 6.0-7.0) (other recommendations suggest slightly acidic soils with a pH of 6.0-6.5, Rubatzky; also 6.0-8.0, Biddle);
  • humus content (according to I. V. Tyurin) – not less than 2%;
  • mobile phosphorus and exchangeable potassium (according to A.T. Kirsanov) – at least 150 mg/kg of soil.

Beans grow best in neutral soils. For example, most soils in South America and Africa are acidic, high in aluminum and manganese and low in phosphate, so it is common practice to correct the pH by liming, since beans are susceptible to aluminum toxicity.

In northern areas light, well warmed soils are considered the best for beans. In cold soils with a shallow groundwater table this crop decreases productivity; stagnant water in such soils during 2-5 days leads to the death of plants.

Of the bean species, tepari, lima and mung bean are less sensitive to soil salinization.

Compacted, heavy, clayey, poorly heated soils with a high groundwater table, dense solonetz and very light sandy soils are unfavorable for cultivation. The bean yield is greatly reduced on damp peaty soils.

For an early harvest, seedlings are planted on southern slopes protected from cold northern winds.

Vegetation

The growing season is (60) 75-120 (200) days and depends on the variety, weather conditions, and latitude of the area. The growing season lengthens in the north and shortens in the south.

Under favorable growing conditions, bush beans can yield a crop in 60-70 days; trellised beans usually require 10-20 days more.

For common beans, the phases of vegetation are accepted:

  • sprouting;
  • the first true leaf;
  • budding;
  • flowering;
  • ripening.

The diverse production areas and growing systems of Phaseolus beans provide a wide range of agronomic requirements and management practices, whether the beans are grown as a large-scale green vegetable for processing, hand harvested for the fresh market, as dry beans for direct sale, or for processing into canned beans. The choice of soil type is important for the rapid establishment of a relatively short-season crop, which limits large-scale Phaseolus bean production to certain geographic areas where effective mechanization is available.

Flowering of bush forms of common bean lasts 15-20 days; curly forms last 30-35 days. Flowering within an inflorescence begins with the lowest flower and spreads upward along the flower stalk. On average the flowering of the brush lasts 10-14 days, the whole plant lasts 20-30 days. If beans are harvested, the flowering period drags on for up to 30-40 days. The duration of flowering depends on the growth pattern of the plants. Varieties with determinant growth bloom 12-16 days, with indeterminant – 23-25 days.

Flower initiation and development is significantly delayed at sub-optimal temperatures. At temperatures below 10°C, fertilization may not occur, and if partial seed development does occur, the pods are small and irregularly shaped. Flower drop and ovary abortion can be caused by temperatures above 35°C.

Lateral branching provides more flowering nodules and increases flowering time and yield potential. Branching is also useful because it allows differentiation of flower and pod development. This characteristic is useful, especially after flower or pod drop, because renewed flowering is possible. Because bean varieties usually have more lateral branching, they are usually better adapted to stress. Determinant varieties are more susceptible to stresses that interfere with pod establishment, which can result in low yields at a single harvest. However, under favorable growing conditions, determinate plants have the advantage of uniform pod development. To improve its edible qualities, plant breeders have developed varieties of beans with slow maturation of seeds.

The size of the bean increases during the first 10 days after flowering by about 1 cm per day. As the beans form, the intensity of flowering decreases and even the already formed blossoms drop off. Depending on the growing temperature, beans are usually suitable for harvesting about 7 to 15 days after ovulation, although the best pod quality is achieved when the pods are harvested to full lengthening. Harvesting can be done selectively as the beans mature or all at once. Determinant varieties are suitable because they have a small gap of 2-6 days between the total flowering time and flowering, which produces the maximum number of beans suitable for single harvesting.

Crop rotation

Main article: Leguminous crops of the crop rotation

Beans in the crop rotation are usually placed after winter cereals, sugar beets, potatoes, and other crops. If there is a risk of sclerotinia, beans are not placed after sunflowers.

Root crops, onions, cucumbers, tomatoes, potatoes are considered the best predecessors of vegetable crops.

They may be used for reseeding winter crops with poor overwintering.

Beans are row crops, so they are a good precedent for many field crops including grains in crop rotations. In the North Caucasus, for example, winter cereals are placed after beans.

Crops that leave coarse post-harvest residues (corn, sunflower, cabbage) as well as crops of the legume family are considered bad predecessors of beans. Beans can be returned to their original place no earlier than 4-5 years later.

Fertilizer system

Most varieties have a relatively small root system, and because it often has limited absorption capacity, additional fertilization is usually necessary. Determinant varieties in particular do not have early or adequate access to rhizobia-fixed nitrogen, so fertilization is necessary for vigorous crop development. The nitrate form of nitrogen is preferable to the ammonium form. Phosphorus is especially important during early plant growth. Fertilizer rates should take into account plant density.

In general, beans are thought to be a low nitrogen-fixing crop, and in many experiments, beans responded well to high nitrogen applications. Although rhizobia are present in soils, especially in South America, nitrogen-fixation levels are often insufficient to maximize the potential of the crop during its relatively short life span. A wide range of strain-specific rhizobia are thought to be present in some soils, and specific interactions between strains and varieties can be significant. In North American dry bean seed production, the use of rhizobia inoculum is not practiced, so nitrogen is applied as a fertilizer before planting. In general, U.S. growers apply 150 to 250 kg of nitrogen/ha before planting, either in the spring or the previous fall. More recently, granular soil inoculants have emerged that, when applied with the seed at planting, reduce the amount of nitrogen fertilizer (Biddle, 2009).

On poor soils in the Non-Chernozem zone, nitrogen fertilizers N10-25 are also applied to beans in spring because young plants cannot fully cover their nitrogen needs from the weak activity of symbiotic nodule bacteria.

Beans are sensitive to salinity, so seeds should not come into direct contact with fertilizer when sowing.

On soils poor in organic matter organic fertilizers should be applied under its predecessor. In the Non-Black Soil Zone on poor soils, organic fertilizers can be made directly under the beans in an amount of 10-15 tons/ha.

At the fall treatment under the plowing bring phosphorus-potassium fertilizer in an amount of P45-80K45-80. Responds well to the introduction of ash.

During sowing, row-wise application of phosphorus fertilizers at P10-15 is recommended.

Phosphorus deficiency is most common in all acidic soils of the world. The plant remains dwarfed, the stems thin with short internodes. The upper leaves remain small and dark green, while the lower leaves turn yellow with necrosis along the edge.

Potassium deficiency causes yellowing and necrosis of leaf tips and edges, but symptoms are not often seen in the field because other factors, such as lack or excess moisture, can often mask symptoms. It is common practice to apply a combined fertilizer containing N, P, and K.

Fertilizer requirements for beans (Defra, 2010, UK) depending on soil index (ADAS classification):

  • index 0 (very low) – N 180 kg/ha, P2O5 200 kg/ha, K2O 200 kg/ha;
  • index 1 (low) – N 150 kg/ha, P2O5 150 kg/ha, K2O 150 kg/ha;
  • index 2 (medium) – N 120 kg/ha, P2O5 100 kg/ha, K2O 50-100 kg/ha;
  • index >2 (high) – N 80 kg/ha, P2O5 50 kg/ha, K2O 50 kg/ha.

Micronutrients

Beans often suffer from micronutrient deficiencies or toxicity.

Sulfur deficiency is manifested by the entire leaf becoming chlorotic in the lower part and then affecting the upper leaves. This problem is especially true when using compound fertilizers that have little or no additional sulfur.

Zinc deficiency causes interstitial chlorosis of young leaves, and necrotic spots appear on the surface of the leaves. Zinc is particularly deficient in alkaline soils in some countries of the Americas and Australia.

Boron deficiency usually occurs soon after germination, when the beans are still small. In severe cases, the growing point dies off and secondary bud growth occurs. Beans are very sensitive to excess boron in the soil.

Manganese toxicity occurs in volcanic soils with a pH of less than 5.5 and can also be caused by excessive application of ammonium sulfate.

 

Irrigation

Dry seed beans are grown in many regions of the world that experience periods of low rainfall and high temperatures that can exacerbate the effects of drought on bean production. Irrigation is not always available at a cost-effective price in many developing countries, although small producers have developed systems that use ridges and furrows to allow irrigation canals to supply water when needed. In large production systems in regions such as Central America, where beans are often planted at the end of the rainy season, initial soil moisture is usually adequate and the stress period depends on when the rains stop. In more northern South American countries, beans are planted at the beginning of short unreliable rainy seasons, but production problems associated with this variability in rainfall can exacerbate drought effects such as salinity, high temperatures, root-damaging pathogenic fungi, and insects.

In North America, large-scale crops are grown by sowing as early as possible in the spring, relying on sufficient moisture in the soil to support early growth, and then relying on rainfall to provide sufficient moisture until the crop matures. However, dry bean seed production requires an average of 380 mm of moisture during the growing season. This can be spring soil moisture, precipitation during the season, and/or irrigation.

The critical period of water demand for dry beans is from late budding to pod formation. Under average climatic conditions, bean daily water consumption peaks at 6-7 mm, but at temperatures above 30°C, beans can use more than 7.5 mm per day. Irrigation after sowing and before sprouting cools the soil and can delay sprouting. Canada prefers to use varieties bred for the short season and less stressed by drought. Studies have shown that yields increase with irrigation when soil moisture is adequate during the growing season and during flowering and pod formation. During the vegetative period, the active root zone is at a depth of 30 cm. Although plant moisture requirements are low at this time, early stress can reduce the number of branches and pod formation sites. During the reproductive period, the active root zone is at a depth of 80 cm. Sufficient moisture during this period is critical to maintain yield. However, frequent watering and maintaining moist conditions at the soil surface during pod formation increases the risk of infection by Sclerotinia sclerotiorum, which causes white mold. Creating and maintaining moisture at a depth of 80 cm before flowering allows you to reduce the frequency of irrigation during pod formation and filling. Irrigation can then be continued as needed until the crop reaches full maturity (Shaw, 2009).

Beans grown for processing have similar water requirements. Because seeds can be planted consecutively, the need for irrigation becomes more important late in the season, requiring irrigation equipment that can be easily moved around the field or between fields.

 

Tillage

Beans are very sensitive to compaction and especially to soil sodding, which can occur on light soil types with poor soil structure, and to soil compaction, which impairs root development. Beans are grown in a variety of cropping systems, including large-scale commercial production of dry seeds or beans for the processed vegetable market, as well as on a smaller scale with less investment in mechanized tillage, seeding, and harvesting.

Tillage is similar to that for other leguminous crops and late spring crops.

Due to the fact that beans are a late sowing crop, 2 soil cultivations are carried out to control germinating weeds. At late sowing dates more treatments (up to 3-4) may be required.

Pre-sowing preparation of the soil is carried out a day or on the day of sowing by the cultivator in a unit with harrows to the depth of the seed or seedling planting.

Sowing

Seed preparation

Bean seeds are very fragile and susceptible to mechanical damage to the seed coat or seedpod, where damage to the dehydrated embryonic plumula can occur as a break in the hypocotyl. Seeds with such damage sprout with no growth point, resulting in a condition known as bald head or snake head. Improvements in seed harvesting equipment, such as the use of rubber bands to separate seeds instead of metal cylinders, greatly reduce damage.

Germination is hypogeal when the radicle expands, pushing the seedpod above the soil surface before the seedling leaves expand.

Seed germination is temperature-dependent, and at soil temperatures below 10°C, the process hardly begins. Beans require conditions that allow for rapid germination and seedling emergence. In some cases, seeds planted early in cool conditions may not germinate well, so several attempts have been made to develop a laboratory test for seed viability. As in the case of peas, the conductivity test showed a relationship between high electrolyte leaching and low germination in the field, but it was difficult to establish an estimate for the test because of large differences in seed size. There seems to be a need for a separate set of results to interpret the germination energy of large-seeded types versus small-seeded types. Another viability test used as an advisory tool in the UK is based on the use of tetrazolium chloride solution, where abaxial surfaces of germs are allowed to soak in the solution after removal of the seedling and the number of germs with areas of uncolored or unreacted tissue is noted. The relationship between large numbers of seeds with undyed areas and poor germination has been shown in the United Kingdom and is used to identify seeds with poor potential for early sowing.

Preparation of bean seeds for sowing consists of sorting and air-heating.

It is recommended to treat the seeds with bacterial preparations.

In case of micronutrient deficiency in soil, it is recommended to treat seeds with microfertilizers:

  • if the content of manganese in the soil is less than 3.0 mg/kg, it is recommended to treat seeds with a solution of manganese sulfate at a rate of 80-120 g MnSO4 per 1 ton of seeds;
    if the zinc content in the soil is less than 1.0 mg/kg, it is recommended to treat seeds with a solution of zinc sulfate at a rate of 150-200 g ZnSO4 per 1 ton of seeds.

When treating seeds with microfertilizer, the adhesive agent NaKMC (sodium carboxymethylcellulose) (0.2 kg/t) is used, the solution consumption should be 10 l/t. Seeds after treatment should have a moisture content of no more than 14%.

A protective fungicide seed treatment is useful to minimize rotting. Seeds are often tested for germination in cold soil to determine their viability under adverse conditions. Varieties with a white seed coat often had poor germination compared to similar varieties with dark colored seeds. Breeders have corrected this feature in new varieties with a white seed coat.

Sowing dates

Dry beans

Dry seed beans have a relatively short growing season; they have shallow roots and are sown during one of the driest periods of the year. They are particularly sensitive to lack of moisture in the soil, and yields can fluctuate when grown without irrigation, depending on weather conditions during growth. Since growth is hardly noticeable at temperatures below 10°C, sowing should begin as soon as this temperature is reached, and since beans are very sensitive to frost, sowing should be done after the danger of frost has passed. In tropical and semi-tropical regions, where there is no winter weathering of the soil, cultivation is carried out shortly before planting and before the onset of the rainy season.

In Russia and Belarus conditions it is recommended to sow beans when the frost is over and the soil is heated to 12-15 ° C at the seed burial depth, or when the soil at a depth of 10 cm warmed to +10 … +15 ° C, and the average daily air temperature will be above +8 . +10 °С. In the south of Russia it is late April – early May, in the middle belt – mid-May. When sowing in cold soil, germination slows down, and seed rotting often occurs. 

In Saratov region bean yield was higher by 0.36 t/ha when sown on May 17-21 at soil temperature 14-18 ° C than when sown on May 8-12, and by 0.26 t/ha higher than when sown on May 27 – June 3.

Too early sowing leads to prolonged absence of shoots and seeds may rot.

 

Fresh beans

String beans are usually harvested during a 6-week season lasting from midsummer to early fall, during which time several harvests, each at a critical stage of maturity, must be harvested to produce a product of consistently good quality.

The timing of the harvest depends on market requirements and the climatic conditions of the season and growing area, particularly the time when soil temperatures reach 10°C and the likelihood of late frosts. In most growing regions, the sensitivity of the crop to cold makes sowing before this time unreliable. Once the appropriate soil temperature is reached, sowing can begin.

A simple but unreliable way to produce a long-lasting crop of fresh beans is to proportionally sow at intervals of 5 to 15 days and use varieties of varying early maturity.

Because string beans are grown during warmer seasons, temperatures at sowing are often similar to those at harvest; hence, with approximately the same length of sowing and harvesting periods, sowing programs can be as simple as sowing for 20 days and harvesting every second or third day. Refinements can be made to this concept, such as slightly longer intervals for early sowing and proportionately shorter for late sowing, and the sowing frequency can be increased during exceptionally warm periods. For string beans, as for peas, an accumulated heat unit (AHU) system can be used, but the baseline temperature at which no apparent growth occurs is 10 °C. If, for example, the maximum and minimum temperatures on a given day are 18°C and 10°C, respectively, the average temperature is 14°C, and after subtracting the base temperature of 10°C, 4 heat units are recorded. To plan seeding using this method, estimate the amount of AHU for the day of harvest and then allow this amount to accumulate between harvests for 1 day or multiples thereof (Gane et al., 1975). Any seeding program may contain varieties with different maturity dates, and these differences must be accounted for in the seeding program.

 

Sowing methods

Seeding method is wide-row. Row spacing in the main areas of cultivation and insufficient moisture is 60 cm, in the northern areas – 45 cm. Sometimes seeds are planted in a shallow furrow, which is then embedded during cultivation.

To obtain high yields, many bush forms are grown at a density of about 40 plants/m2. High densities can be achieved by close rows or by wide-row sowing. This type of cultivation is not suitable for manual harvesting, but is well suited for mechanical harvesting.

Wide row spacing is used to allow repeated manual harvesting when growing beans on a trellis. Trellis planting of beans is usually done about 10 cm apart in a row with a row spacing of 120 to 150 cm. Hill plantings with pole support are spaced equidistant from each other, 90 to 120 cm. Hillside plantings are usually sown five to six seeds per hill, later thinned down to three plants.

Planting density in manual harvesting of bush beans is 45 to 60 thousand plants per hectare, while mechanized harvesting with high planting density grows from 250 to 450 thousand plants per hectare. The use of front-mounted multi-row harvesters has facilitated the practice of high-density narrow-row planting. Although very close plant spacing tends to reduce pod color, this is often an acceptable sacrifice for high yields. However, high planting densities increase the potential for disease. The widespread use of precision seeders provides accurate plant spacing and reduces the amount of seed sown; the high cost of seed also results in lower seed rates.

In some parts of the tropics and subtropics, beans are grown along with or after corn or okra (Abelmoschus esculentus), often using the stems of these crops for support.

In Europe, the USA and other developed regions, large-scale planting operations depend on precision seed drills that can plant beans to a uniform depth with uniform spacing between seeds and between rows. They can be planted in wide beds about 2 m across or with evenly spaced rows across the field. Such planting requires a well-formed seedbed with sufficient moisture for uniform and rapid germination and emergence.

Small-seeded forms are sown by grain seeders, large-seeded – by corn or cotton seeders.

For processing enterprises with combine harvester seeding is produced by seeding machine СПВ-6В or other seeding units on the flat surface with row spacing of 45 cm and the distance between the plants in a row of 8-9 cm. Seed rate of germinating seeds – 240-280 thousand pcs./ha. For conveyor receipt of products and uniform loading of the line with products it is necessary to sow varieties of different groups of ripeness in several terms, usually with an interval of 8-12 days.

For obtaining fresh beans may be used sowing on narrow ridges 10-12 cm in height, with a width of ridges on the surface of 25-30 cm, the width of the inter-row width of 70 cm, between plants in a row – 7-8 cm. For this purpose a combined seeding aggregate АКП-4 can be used. Seeding rate of germinating seeds – 170-200 thousand pcs./ha. Seeding depth: on light soils – 4-5 cm, on medium soils – 3-4 cm. When there is a lack of moisture the depth of seeding is increased by 1 cm. This machine does not require pre-sowing preparation of the soil, as it immediately forms ridges and sows.

In some areas, temperature, the onset of the rainy season, and altitude determine seeding practices (Woolley et al., 1991). In tropical and subtropical areas, beans may be sown along with corn or other crops, and therefore different approaches are taken to sowing them. In these areas, bush and curly forms of beans can be grown either alone or in combination with each other.

Seeding rates

Seeding rate is 0.25-0.4 million germinated seeds per hectare. The weight rate for small-seeded varieties is 70-80 kg/ha, and for large-seeded – 100-150 kg/ha.

String beans respond strongly to changes in plant density. Mechanical harvesters are capable of harvesting beans from several rows, and although beans can be grown in beds where each 1 m wide bed contains four rows, they can also be planted without beds. Usually the width of the row spacing is 50-90 cm, and the distance between the seeds is about 5-10 cm. The seeds are sown to a depth of 5-10 cm, depending on the type of soil and its moisture. The optimum density is 60 plants/m2.

For large-scale commercial production of dry beans in Canada and other countries where large-scale production is carried out, it is mainly sown at a narrow row spacing (50 cm) or wide rows (75-90 cm). The choice of row spacing depends on the cropping system: narrow row spacing is preferred for grain or oilseed crops, while wide row spacing is preferred for those growing other row crops such as potatoes or corn. The plant density is 17-25 plants/m2. Inter-row weeding can be done while the plants are small. After drilling, the soil is usually rolled to compact the soil and stones to reduce soil mass at harvest (Goodwin, 2003).

In small production systems in tropical and subtropical countries, beans may be sown along with corn. Different systems and combinations can be used, depending on land availability and economic conditions. Especially common is the relay rotation of bush or semi-bush beans planted immediately after the corn has matured. A second combination is when beans are planted between rows of corn at the same time, although in some areas the difference between the two harvest periods is several weeks. Another system is to plant beans with other crops such as bananas, cassava, sweet potatoes, coffee and young sugarcane. Each system is described in detail by Woolley et al. (1991). Cross-breeding usually yields low yields, but the advantage for small farmers is reduced risk if one crop fails. Different systems require different seeding densities, which were reviewed by Woolley and Davis (1991).

Sowing depth

Since beans take the cotyledons to the soil surface, the sowing depth is shallow – 3-5 cm. If the top layer dries out, the sowing depth is increased to 6-8 cm.

Mixed crops

In conditions of sufficient moisture bean sowing can be combined with corn and potatoes.

Transplanting method

For the preparation of the nutrient mixture is well suited upland peat.

To obtain the optimum content of nutrients in the mixture in the upland peat add 0.7-0.8 kg/m3 of ammonium nitrate, 0.9-1.0 superphosphate, 0.6-0.7 potassium sulfate, 0.5-0.6 magnesium sulfate, 5.5-6.0 chalk and 5.1-5.5 kg/m3 dolomite meal. Before preparing the mixture it is recommended to conduct a chemical analysis and, if necessary, adjust the recommended doses.

Agrochemical indicators of peat mixture (Outco):

  • pH of the aqueous extract – 5.8-6.5;
  • NH4 – 15-20 mg/dm3;
  • NO3 – 130-150 mg/dm3;
  • P2O5 – 30-40 mg/dm3;
  • K2O – 200-250 mg/dm3;
  • CaO – 170-210 mg/dm3;
  • MgO – 60-70 mg/dm3.

For the cultivation of seedlings suitable plastic cassettes 40 x 40 cm by 64 cells of 65 cm3. Cassettes are filled with substrate and compacted to 3/4 of the volume, then one seed is placed in each cell, fill the rest of the cell and slightly compact it. After sowing, watering is carried out.

Before the germination of seeds air temperature is maintained +20 … +25 ° C, after germination – +17 … +20 ° C, the temperature of the substrate must not exceed +15 ° C. Due to the small volume of the substrate and its rapid drying, watering is recommended several times a day.

The use of cassettes simplifies the care of seedlings and planting in the field. Keep in mind that beans have large seeds and their roots quickly assimilate the volume of soil in the cell. Therefore, no later than 15 days after sowing the seeds into the cassettes, the seedlings (in the phase of two primordial leaves) should be planted in the field. If planting is delayed, the root system extends beyond the ground, the root tips dry out, and the base of the stem becomes woody. Such seedlings are not capable of producing high yields. 

Plant seedlings in the field when the average daily air temperature reaches +14 °C.

Cultivate bean sprouts when weather conditions are warm enough and greenhouses are not required. Cassettes can be placed in well-heated areas protected from cold winds on wooden pallets that can be covered with film. Such constructions are not expensive, and the cost of production remains not very high. If the temperature rises strongly during the day, open the film for ventilation and watering.

For 3-4 days before planting, harden the seedlings: during the day maintain a temperature of +14 … +16 °C, at night +12 … +14 °C with moderate watering. Before planting, the plants are abundantly watered.

The scheme of planting seedlings in the field is determined by the used equipment and technological track of the tractor. Row spacing is usually 60-90 cm, and the distance between the plants in the row is 10-15 cm. Under such schemes, 110-130 thousand plants per hectare. Watering of seedlings at the rate of 0.5 liters of water per plant is mandatory.

Crop care

In case of late sowing and shallow seeding, the soil is rolled with ring-spiked rollers.

After the appearance of the first pair of true leaves and further to the closing of the rows, the care consists in loosening the row spacing. If necessary, the crops are thinned.

In areas intended for mechanical harvesting, foliar feeding with liquid complex fertilizers (LCF) with chelated forms of trace elements for legumes (brand NPK – 5:7: 10 with B and Mo) in the phase of budding is recommended for the growing season, doses of 3-5 l/ha with a working fluid at a rate of 300 l/ha.

In conditions of sufficient moisture is practiced bean plant hilling.

Under irrigation conditions in the south of Russia, as well as in areas with long summers and sufficient moisture, early-ripening varieties of beans are grown after harvesting winter cereals or as a fallow-occupied crop.

Weed control

Young bean plants are uncompetitive, and serious yield losses will occur even when weed pressure is low. In some situations, weeds that accumulate in previous crops, especially when beans follow corn, can increase the slug population that attacks subsequent bean crops.

Bean rust spores (Uromyces phaseoli) accumulate on sagebrush (Oxalis spp.), a common broadleaf weed in bean fields in South America. Weeds can also be reservoirs of and vectors for bean mosaic virus. Poorly weeded crops are exposed to more infection by the virus and develop incompletely, which contributes to further weed growth.

In large-scale production, perennial weeds such as field thistle (Cirsium arvense), field thistle (Sonchus arvensis) and couch grass (Elymus repens) cannot be controlled with chemicals within the crop, so high pressure from these weeds will affect whether or not beans are grown in the field. Other weeds are more difficult to control in the crop, such as creeper weed (Falopia convolvulus) and oilseed rape (canola) or flax seed residues. Green weeds, weed seeds, or berries such as black nightshade (Solanum nigrum or S. americanum) present at harvest can reduce crop quality by staining beans.

In string beans for fresh market or processing, late-growing weeds, such as Stellaria media, which forms a dense mat, or those that weave along rows, such as creeper weed (Falopia convolvulus) and aviculare weed (Polygonum aviculare), greatly interfere with harvest. Taller weeds such as white vermilion (Chenopodium album) and nettle (Urtica urens) are likely to cause less harvesting problems, but have a greater impact on the crop. Mechanical harvesting of string beans is more likely to contaminate the crop with weed stems and flower heads, but litter crops, especially potatoes, pose a risk of contamination with potato berries as well as stems that are very difficult to remove.

Cultural control methods

When growing beans, which are often grown on wider row spacing than peas, mechanical weed control can be done at several stages of crop growth. The critical time for weeding is between 3 and 6 weeks after planting to maintain maximum yield (Burnside et al., 1998). Using the stale bed method first, with watering if necessary, will encourage early germination of weed seedlings, which can then be lightly tilled. Inter-row cultivation after planting should be hoeed to a depth that will not disturb the developing bean roots.

Weeds are less of a problem in intercrops or mixed crops. If beans are grown together with corn, these crops fill more than one ecological niche and thus effectively compete with more weed species. Where beans follow corn, growers place great emphasis on weed control on corn to reduce the number of weed seeds germinating before the beans are planted (Woolley and Davis, 1991).

 

Biofumigants

Biofumigants have been used for many years, and considerable research is continuing on the use of these techniques on annual crops. The technique is based on applying fresh, mulched plant material to the soil that releases several substances that can suppress soil-borne pests or diseases, and in some cases it is claimed to suppress weeds as well. Plants of the genus Cabbage (Brassica) are particularly active sulfur accumulators and synthesize significant amounts of sulfur-rich glucosinolates. Damaged leaves secrete myrosinase enzymes that break down glucosinolates into several products, including isothiocyanates (which are very toxic). Work has shown that these products are active against some soil-borne diseases and pests, but there are claims that weed suppression can also be achieved.

Growing a Brassica cover crop for use as a biofumigant involves establishing a fall crop, usually mustard, particularly brown mustard (Caliente) (Brassica juncea), although other members of the crucifer family (Cruciferae) can also be used.

While the use of such cover crops has several advantages in farming, such as providing a source of nutrients for newly developing crops, helping to improve soil structure by adding organic matter, and having some effect in suppressing pests such as nematodes, there is little reliable information that this technique can become a sustainable weed suppressant in pea and bean crops. It has been suggested that crucifers may have allelopathic effects on weeds, and reports from Europe and North America also suggest that crucifers may be used for integrated weed control (Tollsten and Bergstrom, 1988; Turk et al., 2005). However, there is no reliable evidence of weed reduction in the growing crop (Haramoto and Gallandt, 2005a,b). Similarly, there are reports of suppression of A. myosuroides with a cover crop of mustard preceding spring sowing of horde beans (Jim Scrimshaw), but the effect was not repeated on beans from year to year, although other work on winter cereals has shown significant suppression. This may be due in part to a lack of glucosinolate stability in the soil during weed germination, or other factors may be involved.

 

Herbicides

A limited range of herbicides for this crop is available in the UK and Europe. Diquat, a pre-emergence contact herbicide, kills weeds present at the time of spraying. Pre-emergence applications of S-metolachlor, linuron and pendimethalin plus clomazone are allowed and can provide useful pre-emergence weed control. However, there is a restriction on the use of S-metolachlor. Bentazon is the only post-emergent herbicide for controlling broadleaf weeds. Adjuvant oil can be added for severe weed problems, but the effects of crop damage may increase. Wild oats can usually be controlled by treating the soil before sowing. Cycloxidime controls annual grasses as well as perennial grasses, but not annual bluegrass (Poa annua).

Before crop emergence, it is recommended to treat crops with soil herbicides: Gezagard, KC or Gezagard, SP or Stomp, 33% KC. Later, when weeds sprout we recommend double spraying of crops by fractional doses of herbicide Bazagran: the first – in the phase of 2-3 true leaves of culture; the second – as weeds appear, but not earlier than 7-14 days after the first treatment. Consumption rate of the working solution for one treatment is 300 l/ha.

If beans are grown on narrow ridges or in seedling culture, soil herbicides are not applied, and on the 5th-6th day after sowing, an inter-row treatment is carried out. When weeds sprout, you must conduct double (0.4 + 0.4 l / ha) or triple (0.3 + 0.4 + 0.4 l / ha) spraying of crops by fractional doses of herbicide Bazagran: first – in the phase of 2-3 true leaves of culture; subsequent – as weeds appear with an interval of not less than 7-14 days after the previous treatment.

When using КОУ-4/6 cultivator developed by RUE “Vegetable Growing Institute” with properly chosen working tools it is possible to achieve weeds elimination in row-spacing by 95-98%. Herbicide application with the help of a cultivator sprayer КОУ-4/6 with simultaneous loosening of the row spacing enables to reduce the working liquid consumption to 100-150 l/ha. Carrying out 3-4 such treatments eliminates manual labor for weeding beans crops. During the flowering period, the treatments are stopped, because the leaves and flowers of beans are easily broken.

The herbicide Prometrin, 50% s.p. in an amount of 3 kg/ha of the drug can be used against weeds on the bean crops. Spraying is carried out 2-3 days before sprouting.

For Vicia and Phaseolus, bentazon is the only material that is safe to use as a post-emergent herbicide to control broadleaf (dicotyledonous) weeds. The selective action of bentazone may be due to differential retention and uptake as well as the ability to metabolize bentazone (see Peas for details).

Harvesting

Green beans (immature seeds)

Yields of green beans increase rapidly in the early stages of maturity, when the crop can be harvested for freezing, while yields increase more slowly in the later stages, when the crop can be harvested for canning.

Although it is not customary to set a sliding fee scale for growers based on the maturity of the crop, it is usually necessary to have an acceptable way of evaluating maturity so that standards can be maintained.

The basic stages of bean maturity can be summarized as follows:

  1. rapid increase in pod length with relatively slow seed development;
  2. Increase in pod length and a more rapid increase in seed;
  3. lignification, stiffening and drying of the pod; and drying and hardening of the seed.

Several methods have been developed that measure the physical changes that occur during ripening, and they are generally a more practical means of determining maturity than any chemical evaluation.

A common evaluation method is based on average seed length. Seed length is measured by measuring the total length of ten seeds, each being the largest seed taken from the largest pod taken from a sample of ten plants. Depending on the variety of beans used, the practical stage of suitability for freezing may be taken between 100 mm and 120 mm of seed length. For canning, the seed length is longer.

Harvesting is carried out by a self-propelled bean harvester equipped with longitudinal picking drums, which rotate along the row, and under the action of spring tines attached to the drum, the pods are removed from the plant. They are lifted into the machine along with a certain amount of leaves and other debris. The pods are then lifted into the cleaning and sorting section of the combine. Light debris (mostly leaves and stems) is blown back into the field. The pod seed separators are able to handle large quantities, and the debris is also blown back into the field. The beans are then unloaded into crates and transported to the plant for processing.

Freezing and canning operations are similar to those described for peas and beans.

For the fresh market (pods)

The decision to harvest beans is based on the stage of bean development. For high yields, the bean pods should reach maximum length before the seeds increase significantly and remain juicy. The ideal situation is when all pods are at the same stage of development. Degree-day measurements are often used in developed countries to predict and plan bean harvests.

Manual harvesting of bush and field beans is common in most countries of the world, since the use of machinery is impractical in many countries. Pole beans with an indefinite bloom period can be harvested for a longer period than bush varieties, so yields are usually higher. In addition to greater yield potential, benefits of pole bean production include better adaptation to conditions with more rainfall, lower moisture inside the leaf canopy, and less disease incidence. In addition, because the pods are less likely to come into contact with the soil, they are cleaner and grow straighter. Nonetheless, bush bean production continues to grow compared to beans on support because of lower production costs.

Start harvesting when beans reach consumer ripeness. During this period, they easily break away from the stalk, the place of breaking is smooth, juicy, the dry matter content of the beans is 7-8%, (at the end of harvesting 9-12%).

The easiest way to determine harvesting ripeness is to measure the length of the seed. Every 2-3 days, ripe beans are picked from 25 randomly selected plants and the length of the largest kernel is measured. Harvesting begins when the average length of the measured grains reaches 5 mm (when the seeds reach a length of 8-10 mm, harvesting stops). The harvested beans are immediately delivered for processing.

The beans must be young (immature), fresh, clean, whole, healthy, with or without a stalk. The color, flavor, and odor of the beans must be consistent with the variety. Must be succulent, fleshy, easily broken when bent, with no bulges of kernels, on a break without coarse fibrous threads and inner skin film, with seed buds. Beans are not allowed to be rotten, flaccid, soiled, steamed, wet, with coarse grains, with a strange odor or taste caused by conditions of cultivation, transportation and storage.

For use as fresh beans are harvested several times by hand, in the morning hours, with simultaneous sorting and subsequent packaging. The beans are packed in wooden crates or low pressure polyethylene boxes tightly, flush with the edges. The net weight must not exceed 12 kg. Packaging containers must be strong, dry, clean, odorless, and ensure the quality, safety, and security of the beans during transportation, storage, and sale.

Several attempts have been made to use machine harvesting of beans, but the damage to the pods is considered unacceptably high for sale in the fresh market. Varieties with very thin pods are known as small beans, which are usually imported into Europe from African countries, particularly Kenya. Small beans are harvested very carefully in order to minimize damage to the pods during transport. Damage to the pods usually occurs during picking and packing, and once the crates are covered with plastic wrap, fungal spoilage can quickly occur in high relative humidity.

For successful machine harvesting, equipment and plants must be compatible. Modern varieties make mechanization easier because they feature concentrated flowering and pod laying, vertical growth with pod laying in the middle or high on the plant, reduced foliage, strong root attachment to the soil, and resistance to some diseases. All of these factors increase the efficiency of harvesting equipment, which uses many metal tines to remove the pods, combing through the foliage. The detached pods and leaves are later separated. Machine harvesting was originally only used for processing crops, since damage to the pods is usually not a serious product defect if the pods are processed within a short period of time. However, the damage becomes easily visible and is not acceptable for harvesting fresh market beans. Many modern mechanical harvesters have been modified to greatly reduce pod damage and are capable of harvesting pods for the fresh market.

Bean varieties specifically harvested for fresh seed (Shelled bean) are harvested when the seeds have reached full size and become relatively hard. The moisture content of the seeds is very high compared to dry bean seeds. Manual labor and/or machines are used to harvest the pods. The seeds are separated from the pods, the latter are discarded because they are fibrous and not juicy.

Bean pods have a high respiration rate, so they should be quickly cooled to about 5°C and maintained at 95% relative humidity. Hydrocooling is the preferred method to achieve rapid cooling and maintain the turgor of the pods. Temperatures below 3°C for more than a few days should be avoided as they contribute to cooling damage. Shelf life of pods of acceptable quality for 2-3 weeks is achieved at 5-10°C and 95% relative humidity.

For processing (dry seeds)

The beans are harvested when the crop is fully ripe, that is, when most of the beans have turned yellow and the seeds have hardened. The leaves have fallen off by this time and the pods are 70-80% ripe.

Mechanized harvesting of some varieties due to low pod attachment to the stem below 10 cm is difficult. Therefore, two methods of biphasic harvesting are used. The first, more common for varieties with pods attached no lower than 10 cm from the soil surface, is to mow plants in swaths with a reaper ЖБА-3,5. The second method is suitable for bush low-stemmed varieties, consists in rubbing and laying in swaths by a bean-cutting machine ФА-4. The mowed swaths are then picked up and threshed by a CK-4 harvester equipped with special devices.

On most American and Canadian farms, the beans are trimmed, with the root cut off and the plant laid on the ground. When the beans have dried to 20% moisture, the windrows are picked up by the combine.

The combine is set up so as to cause as little damage to the beans as possible. Bean seeds are very fragile, so the crop is harvested early in the day to reduce seed coat or husk losses. Beans can be damaged by processing when humidity is below 13%. Often in small-scale production, the crop is harvested by hand, either by pulling the above-ground part and spreading it on the ground to dry completely, or by hanging the vines in stacks for drying. Threshing and sorting are often done by hand combing.

Diseases

Main page: Diseases of beans

 

Pests

The main pests of beans:

  • Aphis craccivora (Bean aphid);
  • Cerotoma trifurcata (Bean leaf beetle);
  • Acanthoscelides obtectus, Zabrotes subfasciatus (Bean weevils);
  • Circulifor tenellus (Beet leafhopper);
  • Aphis fabae (Black bean aphid);
  • Diabrotica decimpunctata (Diabrotica);
  • Empoasca fabae; E. kraemeri (Leafhoppers);
  • Lygus hespersus; Chauliops fallax (Lygus bug);
  • Epilachna varivestis (Mexican bean beetle);
  • Apion pisi, A. godmani (Pod borer);
  • Tetranychus urticae (Red spider mite);
  • Sitona lineatus (Root weevil);
  • Hylemya cilicrura (Seed corn maggot);
  • Ophiomyia phaseoli (Stem fly);
  • Thrips tabaci, Heliothrips spp. (Thrips);
  • Bemisia tabaci (White fly);
  • Ascotis, Spilosoma, Amsacta, and Euproctis (Lepidoptera).

The most common nematode pests of beans are species of gall nematode Meloidogyne. Nematodes Pratylenchus spp. are also frequent pests. A rare physiological disease is hypocotyl necrosis, which occurs during germination and is a consequence of low calcium content in the seeds.

Bean seed fly (Delia platura)

Delia platura, or Bean seed fly (seedcorn maggot), is a very common pest found in most temperate climates and affects a wide range of large-seeded crops, including peas, beans, passionfruit, lupine, corn and soybeans. If severely infested, large numbers of seedlings can die, severely affecting the plant population. Late-season pea or bean seeds are attacked by fly larvae during germination. Forage beans (Vicia faba) are rarely affected because they are not often sown in early summer, but late-sown beans and peas for frozen or fresh market are particularly susceptible.

Larvae from eggs laid in fresh disturbed soil feed on decaying plant matter and also penetrate freshly germinated seeds. The larvae feed inside the cotyledons and damage the developing plum and root. Tunneling can occur in the stem and the growth point can be damaged, resulting in the “bald head” or “snake head” symptom, where the stem is elongated but the terminal leaves are missing. Secondary shoots can develop from seeds in peas and forage beans (V. faba), but in beans (Phaseolus) seedlings do not compensate for the damage. Severely infested seeds do not sprout and rot before they emerge. Damage is often noted as spots in the field because flies tend to congregate before oviposition.

In late spring, adults congregate on freshly disturbed soil in fields containing large amounts of green weeds or fresh crop residues. Late-tilled soils that have developed a weed infestation are more likely to be infested with D. platura. The flies lay eggs on the soil surface where the larvae can feed on plant debris and also penetrate large seeds immediately after germination.

To reduce the risk of infestation, all weeds should be buried in seedbed preparation, especially if they have not had time to dry out, and soils with high levels of crop residues, such as carrots, sugar beets or bulb crops, should be avoided. In small-scale production, peas or beans can be protected with fleece or plastic wrap before germination, but commercial crops of beans (Phaseolus) often use insecticide seed treatments.

 

Mexican bean beetle (Epilachna varivestis)

The Mexican bean beetle (Epilachna varivestis), is perhaps the most serious insect pest of dry beans in the western United States. It is thought to be native to the plateau region of southern Mexico, but the insect is found in the United States (in most states east of the Rocky Mountains) as well as in Mexico. In the eastern U.S., the pest is present wherever beans are grown, while in the west the infestation occurs in isolated areas, depending on local conditions and rainfall. The insect is not a serious pest in Guatemala and Mexico, but is very abundant in some areas in the western United States. The southern border of known distribution is in Guatemala, and the northern border is in southern Canada and New England.

Adults of the Mexican beetle overwinter in garbage in fields, along the edges of fields. The beetles enter bean fields in June and July, and the females begin laying egg masses on the plants after they have been feeding for 1-2 weeks. Larvae and adults feed on the underside of leaves, stripping the epidermis from the leaf and leaving a skeletonized leaf.

Pest control includes monitoring and searching for egg masses, allowing the grower to decide in time whether to treat before damage begins (Sanchez-Arroyo, 2015).

Mexican bean beetle (Epilachna varivestis)
Mexican bean beetle (Epilachna varivestis)
Source: flickr.com
©Judy Gallagher (CC BY 2.0)

Seed production

Vegetable beans are facultative self-pollinators and partially (up to 5-10%) cross-pollinating, especially in hot weather.

Bean crops for seed production should be at least 50 m away from other crops in an open area and 20 m away from them in a sheltered area.

Agrotechnics in seed bean farming differs little from the technology on production, except for some peculiarities. All work on the seed plot is carried out in the first place and in the best agrotechnical terms.

Sowing for seed should be carried out on a flat surface at soil temperatures above 10 ° C: Width between the rows of 70 cm, the distance between the plants in a row of 10-12 cm. Seed rate is 135-140 thousand pcs/ha.

During the growing season, three varietal sweeps and approbation are carried out:

  1. during flowering, remove plants with a different flower color from the main cultivar;
  2. plants with a different color and shape of bean are removed during bean ripening;
  3. before harvesting, remove plants that are different in growth, do not match the variety in shape, type of bean, late-ripening plants.

In approbation the crops are inspected at the root. The approbation is carried out at the time of bean ripening by selecting two beans from each plant. On plots of up to 100 hectares, 250 plants in 5 pieces at 50 places diagonally are examined. The shape and size of the bean, the color of the seed rumen, seeds, leaf shape (pointed and rounded), bean type (sugar bean, husky bean) are determined. The sampling of beans is carried out twice: during the consumer ripeness and at the ripening of 2-3 beans. Impurity are plants that differ from the main plants in shape, precocity, type of beans, color of seeds, the shape of the rumen, etc.

Depending on the state of the plants, variety, and soil and climatic conditions, beans are harvested for seed by a single-phase (direct harvesting) or two-phase (split harvesting) method.

The combine harvesting begins when the beans are dry on the plants. If the bunker heap contains wet crop residues, it is immediately sent for drying. After drying, the beans are cleaned on seed-cleaning machines.

Two-phase harvesting method is used in unfavorable weather conditions, in the phase of wax maturity of seeds. They begin harvesting when 50 to 60 percent of beans are dried, which corresponds to about 28 to 30 days after flowering. During this period, the seeds harden and acquire the typical color of the variety. Mowed or handpicked plants are taken to the premises for ripening under mild drying regimes: active ventilation at a coolant temperature of 30-35 °C. Duration of ripening 10-30 days. After drying the seeds to a moisture content of 14-16% threshing bean pile is carried out.

To reduce crushing of seeds during threshing number of revolutions of threshing apparatus is set no more than 400 rpm, but adjusted individually for each variety.

To prevent damage to the seeds bean borer, they are stored at air temperature (± 2 ° C), on a wooden floor, a layer of 1.0 m. The humidity of the seeds should not exceed 15%. When storing beans in bags they should be stacked on board racks. The length of the stack can be different, width of 2-3 bags, height – no more than 6 rows.

Breeding

Dry beans

Cultivated varieties arose from years of domestication of wild species with different seed characteristics. The species with the smallest seed size were related to wild populations, while those with larger seeds were later domesticated and cultivated. Much work has been done on the genetic origin of the species using specific traits, including the seed protein Phaseolin, to try to determine the origin of specific Phaseolus varieties (Gepts et al., 1986).

Kaplan (1965a,b) conducted numerous studies of ancient plant remains of four Phaseolus species in Middle America. These studies suggested that P. vulgaris may have originated in Mexico about 700-400 years ago. It now appears that the bean comes from two main sources: Central American species, which were mostly small-seeded, and Andean species, which were usually large-seeded. Both types were distributed throughout the major growing areas of Central and South America, Africa, Europe, and the United States.

Bean breeding has focused on optimizing some specific characteristics, mainly morphological and physiological. The most obvious morphological difference is the climbing type of growth of the wild plant. The climbing type of growth gives an advantage in wild populations of mixed plants because the climbing stem is able to compete for light among the woody plants and trees that provide support for the climbing bean. Once on the support, the climbing bean wraps itself around it and produces branches that grow at right angles to gravity. These climbing species also produce abundant branches, long internodes, and a large number of knots. Most curly forms are also very indeterminant.

Cultivation has led to a different set of selection criteria, as a greater degree of determinancy makes it easier to harvest. It has also led to shortening the internodes to produce a more compact plant and a plant with enough stem strength to stand on its own, with a loss of twist without the need for additional support.

The descriptor system for the various plant types was developed from the International Center for Tropical Agriculture (CIAT, 1980) and the PI collection in the United States based on seven types (IBPGR, 1982), and was subsequently modified by Leakey (1988).

Suggested description of Phaseolus plant types (Leakey, 1988):

  • Non-determinant curly, long internodes, inflorescences mostly on top of plant – ancestral to the primitive Andean species (P. aborogineus);
  • Climbing with well-distributed pods; limited branching, insensitive to length of day – European and American climbing beans;
  • Indeterminant with short internodes; branches long, little or no branching – numerous strongly branching bush beans, North American Pinto and early European Swiss beans;
  • Indeterminant bush; branches short, growth of main stem and terminal conductor poorly developed; no twisting – a variety common in Middle Eastern germplasm;
  • Indeterminant bush; stem strong, curved; short internodes; side branches of equal growth – black-seeded American varieties. Early sea bean varieties;
  • Upright, indeterminant bush; strong, unbent main stem and branches; poor development of distinct conductor – San Fernando, typical of certain Mid-American varieties;
  • Determinant growth; reproductive buds terminating in the main stem and branches; vigorous and spreading bush, many of the Spanish and Portuguese varieties;
  • Sprawling determinate bush; branching of main stem and branches – several Bush Blue Lake types;
  • Determinant bush; weak branches, few terminal buds – Masterpiece, Diacol, Nima, etc;
  • Determinant bush; vigorous multi-branched; upright lateral branches; short lower nodes – Cimbolo;
  • Determinant bush; open habitus; several well developed branches – Michigan pea bean;
  • Determinant bush; narrowed lower internodes; densely branched; concentrated inner flowering zone – most modern bush varieties of French and Dutch selection suitable for mechanized harvesting.

Cultivation in northern latitudes, such as in Europe, has resulted in different breeding pressures than in the tropics and subtropics. This has been made possible by day neutrality, which provides a greater degree of determinacy and early maturity. Day neutrality allowed for shorter internodes to produce a compact, stiff-stemmed plant type.

Growing conditions have also influenced selection criteria in other climatic regimes in different countries, and growth pattern ideotypes favor (or hinder) differences such as low precipitation, high temperatures, and altitude. In northern latitudes, day neutrality is important when the growing season is short. Photoperiodism is the effect of day or night length on growth and inflorescence, and in legumes, inheritance of the response is controlled by at least two major loci expressing dominance or recessivity, or both (Smartt, 1988).

Leaf size can affect susceptibility to drought stress, and larger leaf area is an advantage in areas with more diffuse light, high altitude, or in the oceanic climates of the world.
Pod dehiscence is an unfavorable characteristic, so preference is given to varieties that have a low frequency of seed shedding. High-fiber pod walls are more prone to split, so selection of low-fiber pods has reduced the likelihood of dehiscence while increasing the taste of the pods when harvested green and consumed as a vegetable.

Seed size and color are also important characteristics, and selection according to certain criteria has led to the wide range of varieties used today. Although wild species often had seed colors ranging from black to brown, including mottled seeds, domestication and subsequent selection has resulted in varieties with larger seeds than wild species and a wide range of seed colors and patterns, including red, cream and white.

Commercial classes of dry beans in the North American literature are usually described in terms of their color and size. These commercial class names are now internationally recognized in the trade.

Red- and pomegranate-red seeds of dry beans

The recessive red allele produces pomegranate-red dark red as well as light red kidney beans (Smith, 1939). Other red bean varieties, such as Mexican red and others, carry the dominant red allele. Many of these red beans lose their color during cooking, but the Stop variety, a small pomegranate red bean that is the same size and shape as the Mexican small red bean and bred on the same gene as the dark red kidney bean, has recently been bred to retain its color during cooking (Leakey, 1999).

White-seeded beans

In the 1960s, four varieties of sea beans developed through the X-ray breeding program at Michigan State University were introduced and evaluated as a potential canning crop in the United Kingdom (Kelly, 2014). There was some commercial interest, and one of the varieties, Seafarer, was re-registered as Purley King and tried for production (Scarisbrick et al., 1976; Evans and Davis, 1978). Although this variety was not commercially successful at the time, new varieties continue to be developed.

Northern beans

Attempts to introduce the northern bean in France were severely affected by bacterial scab (Xanthomonas phaseoli), which is transmitted by seed.

Since then, the disease-resistant Northern bean germplasm has been bred, followed by breeding efforts to develop an early maturing determinant variety with some success in a hybridization program with Leakey’s Horsehead (Leakey, 1999).

 

Dried beans with brown, yellow and green seeds

The color of brown Swedish and brown Dutch beans is due to glucosides of the flavonoid quercetin. Yellow beans, typical of the seasonally very dry Pacific coastal regions of South America, do not contain quercetin, but instead contain the flavonoid kaempferol and its monoglucoside. The yellow beans are known as Canarios, Mantecas and Mayacoba and are known for their digestibility because they contain no tannins. The Prim variety was obtained through extensive crossbreeding and has received some commercial production (Leakey and Harbach, 1975).

The green seeds, due to their stable chlorophyll, were originally selected as French flageolets vert, and many flageolets with green seeds have been bred in France, with some varieties being resistant to anthracnose (Colletotrichum lindemuthianum) (Dean, 1968).

Seed nutritional quality is also being studied, and improving protein content and quality has been identified as potential targets. Reduction of anti-nutritional factors is also desirable because the presence of trypsin inhibitors and lectins affects digestibility. These substances are thermolabile, so beans require a period of complete re-hydration followed by thorough cooking to denature these substances before consumption. Lectins are retained in undercooked or slow-cooked red kidney beans.
Improving seed yields by increasing seed size, reducing pod shatterability, standing ability, and early maturity are all major breeding objectives.

Early maturity is an important characteristic, especially if beans are grown in the more northern temperate areas of the world, where frost can cause serious damage to the crop when it reaches maturity. Cold tolerance is necessary for vigorous early germination (a soil temperature of at least 12°C is required); cool temperatures in the early stages of growth result in short plants and therefore pods that develop close to the ground or on the soil surface, making recovery difficult at mechanical harvest, with a high rate of pod shattering and seed loss. Resistance to heat and drought in the late stages of growth is often desirable in hot summers.

In addition to these morphological and physiological characteristics, breeders seek to develop varieties with increased resistance to a wide range of pests, diseases and disorders. Major pathogens include bean rust (Uromyces appendiculatus), white mold (Sclerotinia sclerotiorum), some viruses, and bacterial mold (Pseudomonas spp.). Selection for resistance to pathogens, especially in the tropics, is very difficult because there are a large number of pathogens; each of them can be transmitted by seeds and almost all of them can be present in several racial forms or strains. Wild Phaseolus species are currently being screened for pest and disease resistance, and some lines have been identified for future development.

In France and the United States, the problem of disease prevention is largely solved by producing seed in disease-free areas due to warm, dry weather conditions that persist throughout the growing season. Seed production in Africa follows a similar practice.

 

Green beans (dwarf French beans, string beans)

Fiberless or snap beans are widely grown and used as a frozen product. The size and shape of the pods varies greatly from variety to variety. For the processed vegetable market, pod size determines the final product.

Green French bean and Romano bean pod sizes (PGRO data, 2013):

  • very thin, Kenyan beans – 6-8 mm;
  • thin, bobby beans – 8-9 mm;
  • medium, fillet beans – 9-10 mm;
  • coarse string, French and some fleshy varieties of Romano – >10 mm;
  • flat string, Italian flat beans – often >15 mm.

Varieties

Depending on the presence of a parchment layer and fibers in the beans, bean varieties are divided into:

  • vegetable (also called asparagus, string beans);
  • grain varieties (peeling).

Vegetable varieties are divided into 6 groups according to the length of the growing season from seedlings to technical ripeness:

  • ultra-ripe – vegetation period up to 46 days;
  • early-ripening – 46-50
  • medium-early – 51-55;
  • middle-ripening – 61-70
  • late-ripening – 76-80;
  • very late – more than 95.

The most common bean varieties: Motol white, Krasnogradskaya 244, Krasnogradskaya 5, Krasnogradskaya 6, Dneprovskaya bomba, Belosemian Frunzenskaya, Dneprovskaya 8, Kishinevskaya stamped 1, Pervomayskaya, Oka, Generous, Oran, Gornal, Nerussa, Biichanka.

Lima beans (Phaseolus lunatus)

Significant quantities of Lima beans are grown for dry, fully matured seeds. The dry seed crop is also harvested by machine and processed in the same way as conventional field beans. Lima beans, being at an earlier stage of maturity than beans, have a higher seed dry matter, protein and carbohydrate content. However, when corrected for moisture content, they are quite comparable.

Origin and taxonomy

Fossils of the large-seeded Lima bean found in Peru have been determined to be over 7,000 years old. Fossils of small-seeded lima beans found in Central America are about 2,500 years old. Wild species are still found in Mexico, Central America and all regions of the Andes. Cultivation is widespread: the crop is grown by subsistence farmers in northern Brazil, and it has become an important major legume crop in parts of Africa and Southeast Asia.

Common names identifying the small-seeded lima bean are siva, and sometimes sea bean. Butter bean and Madagascar bean refer to the large-seeded species. “Fordhook” is the recognized name of the large-seeded group of “potato lima.”

Disagreement over the taxonomic classification of lima beans exists over the species designation of P. lunatus and P. limensis. In an earlier classification, the large-seeded lima bean was assigned to P. limensis and the small-seeded form to P. lunatus; the different forms were assigned botanical variety designations that are often spelled differently. Separate species status for the different lima species is questionable and probably not justified, since all species are interfertile. Currently, all varieties of lima beans, wild and cultivated, are identified as P. lunatus.

Botanical description

Lima bean, or lunatus (Phaseolus lunatus L.) is considered a perennial or annual with a long growing season, but is grown as an annual. There are both climbing and bush varieties. Climbing forms can be up to 3-4 m long, while shrubs can be 50-90 cm tall.

Plants have a highly branched root system of moderate depth, often more than 1 m. The roots are capable of developing nodules containing Rhizobium.

Flowering is indeterminate, the flowers are small, self-pollinated, although cross-pollination sometimes occurs.

Seeds are differently colored, moon-shaped (kidney-shaped), hence the species name. Weight of 1,000 seeds is 250-1,000 g.

The slightly curved oblong pods vary in length from 5 to 15 cm and in width from 2 to 3 cm. Most varieties usually have two to four seeds, though other varieties may have up to six seeds in their pods. The pods are thick in some varieties and relatively thin in others. The beans crack easily. Some varieties have large, flat, oblong seeds up to 3 cm long. Seeds of other species are also flat, but more rounded and about 1 cm long; the seeds of each species are smooth.

Usually cultivars have a light green or white seed coat; others may be red, purple, brown, or black. Two large seed cotyledons make up most of the seed volume. Seeds of wild species are high in cyanogenic glucosides and must be leached before or during cooking. There is little or no glucoside content in modern varieties, especially in light-colored seeds. Nevertheless, consumption of raw lima beans is not recommended.

Cultivated in America, Africa, Asia and some European countries. In Russia it is found in vegetable gardens.

 

Cultivation

Lima beans are more environmentally sensitive than common beans and require warmer weather to grow. The optimum average temperature ranges between 15 and 25°C. Large-seeded lima beans are generally adapted to lower temperatures and higher humidity than small-seeded beans, especially with regard to pollination. For coarse-seeded lima beans, temperatures above 30°C and relative humidity less than 60% during flowering can lead to flower drop. This sensitivity limits production to fairly specific conditions.

An NAA growth regulator has been used to improve pod set.

Seeds germinate well at temperatures between 15 and 30°C; germination is poor at temperatures above or below this range.

Effect of temperature on germination of lima beans (National Garden Bureau, Inc. Downers Grove, IL.):

  • at 10 °C there was no germination;
  • at 15 °C germination occurred after 30.5 days;
  • at 20 °C it took 17.4 days;
  • at 25 °C it took 6.5 days;
  • at 30 °C we had germination after 6.7 days;
  • no germination at temperatures above 35 °C.

The planting depth depends on the seed size and can be from 3 to 6 cm, with large-seeded varieties planted deeper. Sprouts appear most quickly at a temperature of about 25°C. Seeds are very susceptible to mechanical damage.

Lightly textured, warm and well-drained soils produce higher yields than using shallowly textured soils. A slightly acidic soil with a pH of 6-7 is also preferred. Except for temperature restrictions, cultural procedures for lima beans are similar to those for beans, but the longer growing period requires more moisture and nutrients. Lack of moisture is most critical during flowering. Additional nutrition is usually provided by fertilizers containing nitrogen, phosphorus, and potassium. The response to nitrogen fertilizer application is higher than for beans.

Many of the same diseases and pests that affect common string beans and other legume species also affect lima beans.

In bush planting, the usual distance between rows is 60-90 cm with a row spacing of 10-15 cm. Varieties grown on staves are spaced wider so that they can be harvested by hand.

Harvesting

Depending on the variety and growing temperature, the period from sowing to harvest can be 70 to 110 days, and longer at low temperatures. Compared to string beans, which are usually grown for their fleshy pods, lima beans take longer to harvest to produce enlarged but immature seeds. As the seeds mature, the color of the seed coat changes from green to cream or white. During seed maturation, the pod becomes bulging as a result of enlarged seeds. At harvest stage for fresh use, the pods are green and the moisture content of the seeds is 60-70%. Because of different flowering times, the pods ripen unevenly, which is less important for fresh use than for processing.

Because of the high labor intensity of manual harvesting, much of the fresh crop is harvested by machines. The difficult manual removal of immature seeds from the pods is an additional incentive for mechanization. Dwarf plants with a determinant type of flowering are required for efficient harvest mechanization. Yields of fresh green lima beans in the rind are 2 to 3 t/ha.

Harvested mechanically, peeled lima beans have a short post-harvest period, so they are processed as soon as possible, usually by freezing or canning. Beans of varying degrees of maturity are separated by specific gravity using saline solutions. Freshly picked lima beans in pods can be stored in good condition for several weeks at 5-7°C and 90% relative humidity. At lower temperatures damage from refrigeration can occur.

 

Tepari bean (Phaseolus acutifolius)

Tepari bean (Phaseolus acutifolius A. Gray var. latifolius G. Freem.). It is represented by bush forms.

The tepari bean originated in northern Mexico and the southwestern United States, where it was probably first cultivated about 5,000 years ago. The advantages of this plant are resistance to high temperatures, low relative humidity and drought tolerance. The pods can set at high temperatures (35°C), while with other Phaseolus species this is not possible.

The cultivated plant is a low-growing, semi-erect annual with a short day; the wild forms are mountain plants. The inflorescence is cystic on a short pedicel. Flowers white or pale purple. Pods small, flat, short with a beak, 6-7 cm long, hairy. Seeds are small, flat, and their color varies greatly. Weight of 1000 seeds is 100-140 g. Seeds take about 60-90 days to mature; dried seeds contain about 60% carbohydrates and 22% protein.

Cultivation of the tepari bean has been limited to its specific climatic niche and is mainly grown by indigenous peoples in the southwestern United States. The crop has been introduced to Africa, where its production is limited, and it is grown almost exclusively in areas with high temperatures and limited rainfall. Tepari beans are resistant to common bacterial damage, and breeders have transferred this resistance to common beans.

 

Sources

V.V. Kolomeychenko. Horticulture/Textbook. – Moscow: Agrobiznesentr, 2007. – 600 с. ISBN 978-5-902792-11-6.

Horticulture/P.P. Vavilov, V.V. Gritsenko. Vavilov. ed. by P.P. Vavilov, V.S. Kuznetsov et al. – M.: Agropromizdat, 1986. – 512 p.: ill. – (Textbook and Tutorials for Higher Education Institutions).

Fundamentals of agricultural production technology. Farming and plant growing. Ed. by V.S. Niklyaev. – Moscow: “Bylina”. 2000. – 555 с.

Modern technologies in vegetable production / Dr. A.A. Autko [etc.]; edited by A.A. Autko. – National Academy of Sciences of Belarus, Institute of Vegetable Growing. – Minsk : Belarus. nauvuka, 2012. – 490 p., [16] l. ill.

World vegetables : principles, production, and nutritive values / Vincent E. Rubatzky and Mas Yamaguchi. — 2nd ed. 1996.

Peas and beans. Crop production science in horticulture / Antony J. Biddle. 2017. UK.