Peanut (Arachis hypogaea L.), or groundnut or Chinese nut, is a food leguminous and oil-bearing agricultural crop.
Other names: Goober, pindar, earth nut.
Source: commons.wikimedia.org©Pau Pámies Grácia (CC BY-SA 4.0)
Economic importance
Roasted seeds and extracted seed oil are used worldwide.
Peanut seeds contain a large amount of protein 25-35% and fat (oil) 40-60%, 10-25% carbohydrates, as well as vitamins. It is used as a raw material for obtaining non-drying vegetable oil (iodine number 83-103), which is used for making the highest kinds of preserves, confectionery products and margarine. The oil is also used in the soap and pharmaceutical industries.
A waste product of the oil production is cake of high quality, with up to 45% of protein and up to 8% of fat. The cake is used for making halvahs, cookies and other food products.
Protein content in the dried leaves and stems is 11-19%, which are used for fodder purposes, the quality of which approaches the hay of clover and alfalfa.
Peanut husks (bean cores), which weigh about 25-35% of the weight of the beans, can be used as an organic fertilizer, for the production of insulation materials and as fuel.
Whole beans are also in demand in their natural form.
The tender shoots and leaves are used as herbs and the immature pods are used in cooking.
History of the crop
Early domestication occurred east of the Andes Mountains in southwestern Brazil, Bolivia, Paraguay or northern Argentina, which is the possible center of origin and from where it penetrated first to the Philippine Islands, then to Japan, China and India.
The peanut has been cultivated for over 5,000 years.
In Europe, it came from China in the 16th century.
In Russia this crop first appeared in 1825 in the botanical garden of Odessa.
Cultivation areas
Nowadays peanuts are grown in all the tropics, most of the subtropics, and, in the absence of frost, even in temperate zones up to 40° latitude from the equator.
In 1984 the world area of groundnut sown area amounted to 18,3 mln ha.
At the end of the twentieth century, peanuts were sown on about 24 million hectares or 15 percent of the world’s leguminous crops. The gross harvest was approximately 31 million tons or 14% of total grain legume production.
The main peanut producers are India, China, Japan, Indonesia, Korea, Burma, Central and North Africa. Asian and African countries account for 80% of global production. Small areas are occupied by peanuts in the USA and in the Mediterranean countries.
In Russia peanut acreage is insignificant; it is cultivated mainly in Krasnodarsky krai. It is also cultivated in the south of Ukraine, in countries of the Caucasus and Central Asia.
Yields
The average yield in the world is 1.3 tons per hectare.
As of 1986, bean yields in the USSR were 1.5-1.8 t/ha. Under irrigated conditions it reaches 3.5-4.0 t/ha. The maximum yield was recorded at the Andijan variety site (Uzbekistan) and was 6.1 t/ha.
Botanical description
Groundnut (Arachis hypogaea L., ssp. vulgaris L.) is an annual herbaceous plant of the legume family (Fabaceae), there are also perennial forms. Most cultivated plants are tetrapioids.
Of the two main plant forms, the shoot type is prostrate and spreading, while the wisp type is more erect and less spreading. Both species are about 60 cm tall.
Two forms are used in culture: bushy and stalky. In Russia, the bush form is more important.
The root is strongly branched, penetrating into the soil to a depth of more than 1.5 m.
The stem is branched. The bush branches are rounded at the base, tetrahedral and pubescent at the top.
Leaves are pairs-pinnate, the upper side of the leaf blade glossy, the lower one pubescent.
Flowers are arranged in axillary racemes in (1) 2-3 pieces. The corolla is yellow or orange.
Above-ground flowers are cross-pollinated. Peanut also has underground (cleistogamous) flowers, which do not open and are pollinated by self-pollination.
After fertilization, the bases of the ovaries of the above-ground flowers begin to proliferate to form gynophores. Gynophores grow upward for 5-6 days, then bend and embed the ovary into the soil to a depth of 8-10 cm. After that, a fruit begins to develop from the ovary.
The fruit is a non-dehiscent, cone-shaped pod. The valves are thick, loose, with a net-like surface.
The seeds are oblong-oval and rounded, dark red or light pink. The number of seeds in a pod varies from 1 to 7 (usually 3-5). Weight of 1000 beans – 600-1500 g, 1000 seeds – (200) 300-400 (500) g. The weight of valves of pods is 25-35%.
Biological features
Temperature requirements
Peanuts are a very heat-loving crop. Seeds germinate at a temperature of at least 12-14 °C.
Sprouts cannot tolerate frosts of less than -1…-1.5 °C. Autumn frosts of -0.5…-1 °C (Kolomeychenko; according to other reports, -2 °C, Vavilov) also damage the above-ground part of plants. At -3 °C, seeds of freshly plowed pods lose germination.
The optimal temperature for plant growth and development is 25-28 °C.
At temperatures below 12 °C, fruits do not form.
Moisture requirements
Peanut is a humid crop. It is most sensitive during the period from the beginning of flowering to the end of fruit formation. If there is a lack of moisture during this period, flowering and formation of fruits stops, and the bean yield decreases sharply.
From sowing to flowering peanut plants are less demanding of moisture and can even tolerate drought.
By the phase of bean maturity, the need for valga also decreases. Excessive moisture in late August leads to a prolonged growing season and delayed bean maturation.
Light requirements
Peanuts are a light-demanding crop with a short daylight period.
Some varieties require a short day to bloom.
Soil requirements
Peanut is demanding for fertility, friability and drainability of soils.
Optimal soils are chernozem soils of light texture, as well as sandy soils. Soils with a light texture promote bean penetration and development, which usually occurs below the soil surface. The presence of calcium in the soil is important for good seed development.
Saline and waterlogged soils are unsuitable for its cultivation.
Vegetation
Peanuts vegetation period is 120-160 days.
Vegetation phases:
- sprouting;
- budding;
- flowering;
- ripening.
In planted seeds, neither hypogeal nor epigeal germination is observed; rather, the seeds are pushed to the surface by the hypocotyl and remain on the surface (according to other data, the seeds are not brought to the surface). Further growth occurs due to elongation of the above-ground epicotyl. Propagated usually by seed; cuttings may be used, but rarely.
Bunch-type varieties, also known as Spanish or Valencian peanuts, are early and harvested after 3 to 5 months. Shoot or Virginian-type seeds take 6 months or more to mature. Mature seeds are virtually dormant, so a delay in harvesting can lead to germination of seeds inside the pod.
Crop rotation
Main article: Leguminous crops of the crop rotation
In crop rotations, peanuts are placed after winter crops (winter wheat), corn, castor beans, sesame, or vegetable crops.
As with other legume crops, peanuts are a good precedent for many field crops, such as corn and cereals.
Fertilizer system
Peanuts are nutrient-demanding. For the formation of 100 kg of seeds and the corresponding amount of vegetative mass, it takes out of the soil 6.2 kg of nitrogen, 1.1 kg of phosphorus and 4 kg of potassium.
Peanut responds very well to fertilizers, especially phosphorus fertilizers. On leached chernozems Pre-Caucasus and chestnut soils also responds to nitrogen fertilizers, especially in the weakened activity of nitrogen-fixing bacteria.
The recommended rates of fertilizers (at a planned yield of 1.5-1.8 t/ha) are 10-15 t/ha of manure (or other organic fertilizers) and P40-50K20-30.
A good economic effect is given by pre-sowing nitrogen-phosphorus fertilizers (N10P10). During the growing season, additional nitrogen-phosphorus fertilizers at the beginning of the phase of flowering – the formation of ovaries.
Tillage
The system of tillage for peanuts is similar to that for other late row crops and includes
- autumn plowing to a depth of 25-30 cm (with preliminary discing when placing peanuts after winter cereals);
- harrowing in early spring;
- 2-3 cultivation with subsequent harrowing.
Sowing
Seed preparation
Seeds with purity of at least 90% and germination of at least 85% are used for sowing.
Pretreatment of seeds with bacterial preparations, such as nitragin, as well as treatment with 80% TMTD at the rate of 6 kg/t of seeds gives a good economic effect. According to Tashkent Agricultural Institute, treatment of seeds with nitragin increased the yield by 0.85 t/ha.
Husked seeds are usually used for sowing, but whole or broken into 2-3 parts pods can also be used for this purpose. The use of husked seeds, according to the Kherson breeding experimental station of melon allows you to increase the yield by 0.2-0.6 t/ha than when using whole or split pods.
Large seeds give the highest bean yield. Small and shriveled seeds are not used for sowing.
Sowing dates
Sowing peanuts begin when the tilled layer of soil at a depth of 10 cm is heated to (13) 14-15 °C. Sowing of split or whole pods may be started 5-7 days earlier.
Sowing methods
The seeding pattern should provide a feeding area of 70x(25-30) cm in rainfed conditions and 70x(10-15) cm in irrigated conditions.
In continuous plantings, the distance between plants of the bunch type may be 30 x 60 cm or 15 x 75 cm; more space is allowed for the shoot types.
Peanuts are often sown with other species.
The most common sowing method is wide-row with a row spacing of 70 cm. Corn or cotton seeders are used for this purpose.
Peanuts can be cultivated in a square-nesting way under the scheme 70×70 cm by 6-8 plants in one nest. This method has an advantage because it increases the yield and reduces labor costs for the care of crops in 1,5-2,0 times.
Seeding rates
Seeding rate of hollowed seeds is (30) 50-80 kg/ha. The rate increases by 25% for seeding with whole or split pods.
The optimum density of plant stand is 100-120 thousand per hectare.
Sowing depth
Sowing depth is 6-8 cm and depends on moisture and granulometric composition of the soil.
Crop care
Care of crops comes down to maintaining the soil in a loose, weed-free state. It consists in:
- pre-emergence harrowing;
- 3-5 inter-row cultivations to a depth of 6 to 8 (10) cm with row weeding;
- 1-2 hilling during flowering and the appearance (burrowing) of gynofor.
Hilling gives particularly good results when irrigated.
Harvesting
Peanut harvesting begins when the beans are well made, it is easy to separate from the gynophore, the seeds from the valves. Also, during this period, there is a partial yellowing of the leaves, darkening of the inner side of the bean valves and the presence of seed color characteristic of the variety. In the conditions of the Krasnodar Territory, early ripening varieties ripen in the first ten days of September. Hot and dry weather during pod ripening is desirable for seed development and quality.
Harvesting is carried out in a two-phase method. For this purpose, a two-row peanut-harvesting trailed machine ЛП-70 is used, which prunes the roots, extracts the bushes from the soil, shakes them off the ground and puts them in a swath. Swaths are formed in 2-3 passes of 4-6 rows of peanuts. The threshing of swaths begins 3-5 days after digging, when the humidity of the pods decreases to 20-25%.
To select and thresh the swaths (separation of pods) using combine harvesters, such as СК-5 with a device МА-1,5.
In the case of late fall harvesting and wet weather, the pods are dried at a temperature not exceeding +40 °C on special decks layer thickness of 5-7 cm with constant agitation.
The humidity of the pods before storage should not exceed 8%.
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.
World vegetables : principles, production, and nutritive values / Vincent E. Rubatzky and Mas Yamaguchi. — 2nd ed. 1996.