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Castor bean

Castor bean or Castor oil plant (Ricinus) is a tilled oilseed crop.

Economic importance

Castor seeds contain from (40) 47 to 52 (59)% non-drying oil. In the kernels, the oil content reaches 65-70%. The oil has a high viscosity, does not harden at low temperatures (up to 16 °C), the iodine number is 82-86, and does not ignite at high temperatures. The seeds contain poisonous substances – ricin, the chemical composition of which includes a cyan group, and a less toxic alkaloid ricinin (toxalbullin).

Castor bean seed oil is obtained by hot pressing the seeds or by solvent extraction. Castor oil obtained by these methods is used in leather, textile, paint and varnish, soap, perfume, metalworking and other industries. The oil obtained by the cold method is used in medicine and is called castor oil. Castor oil and castor oil differ in different content of toxic substances: they are partially present in castor oil, and practically absent in castor oil.

Castor oilcake is used to produce casein glue and as an organic fertilizer with a nitrogen content of up to 7.5%, up to 2% phosphorus. It is not suitable for livestock feed without pre-treatment, as it contains toxic substances. At oil mills, castor oil cake can be decontaminated, after which it is permissible to feed it to animals in small quantities. 100 kg of oilcake correspond to 92 feed units and contain 2.6 kg of digestible protein.

Castor bean leaves can be used to feed silkworms.

Crop history

The homeland of the castor bean is tropical Africa, where it is still found in the wild. Also found in the countries of Western and Central Asia, Afghanistan and India.

It began to be cultivated in ancient times in Egypt, from where it later spread to Asia, America and Europe.

In Russia, castor beans began to be grown in the second half of the 19th century. The first mention of it dates back to 1840.

Cultivation areas and yield

In 1986, the area sown with castor beans in the world was about 1.5 million hectares (or 1% of all sown areas occupied by oilseeds), of which 500 thousand hectares were located in India, more than 400 thousand hectares – in Brazil . There are small areas under crops in Italy, Argentina, Romania, Hungary, Bulgaria, China, and African countries. The gross harvest of oilseeds was 1.4 million tons.

In the USSR in 1986, the sown area was about 140 thousand hectares.

The main areas of castor bean cultivation in Russia are the North Caucasus, the Rostov Region, the Krasnodar and Stavropol Territories. Also grown in the south of Ukraine.

The average seed yield is 0.8-0.9 t/ha. The maximum yield is 1.5-2.0 t/ha.

In Russia, the yield is usually 0.5 t/ha, in the USSR – 0.8 t/ha.

Botanical description

Cultivated castor oil belongs to the genus Ricinus , family Euphorbia ( Euphorbiaceae ). The genus Ricinus includes three species:

  • castor bean (Ricinus microcarpus g. Pop);
  • large-fruited castor bean (Ricinus macrocarpus g. Pop.);
  • Zanzibar castor bean (Ricinus sansibarinus g. Pop.).

In Russia and on the territory of the countries of the former USSR, two types are cultivated: small-fruited castor bean and large-fruited castor bean. These species have subspecies, of which the Persian castor bean (Ricinus microcarpus ssp. persicus g. Pop.) and the blood-red castor bean (Ricinus macrocarpus ssp. sanguineus g. Pop.) are of the greatest agricultural importance.

In the tropics and subtropics, castor bean grows as a perennial plant. Plants under these conditions reach a height of 10 m, with a well-developed crown and thick stem. In our country, it is cultivated as an annual crop, as it dies in winter.

Root

The root is taproot, penetrates to a depth of 3-4 m and spreads to the sides up to 2-2.5 m.

Stem

The stem is straight, hollow inside, strongly branched.

Plant height 1-3 m or more.

Persian castor bean plants are shorter, with a green stem and a waxy coating. Blood red castor bean plants have a red or brown stem without a waxy coating.

Leaves

The leaves are large, on long petioles, palmately incised, with 7-11 lobes.

In Persian castor beans, the color of the leaves is green, in blood red – green with red veins.

Inflorescence

The inflorescence is a raceme, up to 80 cm long in Persian castor beans, up to 60 cm in blood-red ones. 2-12 inflorescences are formed on one plant.

In the upper part of the brush are collected female flowers, in the lower part – male. In one brush there are from 50 to 200 flowers. Flowers are small, dioecious. Perianth simple, five-petalled.

Male flowers with numerous stamens. Female – with a three-celled ovary and three two-lobed stigmas.

Plants are cross-pollinated.

Fruit

The fruit is a three-celled spherical or elongated capsule, which contains one seed in each nest. The surface is smooth or covered with thorns, the thorns become prickly when ripe.

The boxes located on the central brush ripen first, the lateral ones later.

In the Persian castor bean, the ripe bolls crack and the seeds spill out. In blood-red castor beans, the boxes do not crack.

Seeds

Seeds are oval-ovoid, with a shiny brittle shell, variegated. In the seeds of the blood-red castor bean, a dark brown color predominates and there is a clearly expressed papillary outgrowth – caruncle, in the Persian castor bean, gray color prevails, and the caruncle is less noticeable. Persian castor seeds are smaller than blood red.

The weight of 1000 seeds is from 200 to 500 g.

Biological features

Temperature requirements

Castor oil is considered a heat-loving plant.

Seeds begin to germinate at a temperature of 12-13 °C, at 10 °C only single shoots appear. The optimum germination temperature is 16-18 °C.

Seeds germinate in 8 days at 15 °C, 4-5 days at 20 °C, and 2-3 days at 25-30 °C.

Normal development of plants requires 25-30 °C (Vavilov). According to other sources, 20-25 °C (Kolomeichenko). In cool weather, the ripening period increases significantly, and the yield and oil content of seeds decrease.

Seedlings and adult plants can be damaged when the temperature drops to -2 °C.

The intake of nutrients in castor beans increases at a temperature of 30-35 °C.

Moisture requirements

Castor oil is demanding on moisture. The amount of precipitation during the growing season should be at least 300 mm.

High yields are possible only under conditions of sufficient moisture or irrigation. In dry years, leaves fall off the plants, flowers and boxes fall off. With a lack of moisture, the yield and oil content of seeds decreases sharply.

Thanks to a powerful and developed root system, plants are able to tolerate short-term droughts.

Soil requirements

Castor oil is demanding on the soil. Optimum (sandy and loamy) chernozems and gray soils, rich in nutrients and well aerated.

The optimal reaction of the soil solution is pH 6.0-7.3.

Heavy clay, light sandy, swampy, floating, saline and alkaline soils are unsuitable for cultivation.

Light requirements

Light-loving short day plant.

Vegetation

Vegetation period of castor (90) 100-120 (150) days.

Phases of growth and development of castor beans:

  • seedlings;
  • 2nd real sheet;
  • 4-5th sheet;
  • the formation of inflorescences;
  • bloom;
  • maturation.

Crop rotation

In a crop rotation, castor beans are usually placed in a tilled field after winter wheat, corn, and legumes. Also, the predecessors can be winter crops going through a clean or busy fallow, spring and winter cereals going through a layer of perennial grasses and after tilled crops.

Castor oil can serve as a good predecessor for spring grain crops, sunflower, with good agricultural technology – winter wheat, and in some regions of the North Caucasus – winter.

Because of the danger of being affected by Fusarium, castor oil is returned to its original place in the crop rotation no earlier than after 8 years.

The root system of the castor bean depletes less water compared to sunflower and has a good effect on soil structure.

Fertilizer system

Castor beans are demanding on nutrients.

For the formation of 100 kg of seeds from the soil, 7.2 kg of nitrogen, 1.7 kg of phosphorus, 5.9 kg of potassium are absorbed.

The best fertilizer for castor beans is manure, which significantly increases the yield of seeds. According to the experiments of All-Russian Research Institute of Oilseeds, when manure was applied, the seed yield increased: in the Krasnodar Territory – by 34.7%, in Ukraine – by 41%, in the countries of Central Asia – by 26-28%. The recommended rate of manure application is 20 (30) t/ha for autumn tillage.

Castor oil responds especially well to the application of phosphorus and nitrogen fertilizers. According to All-Russian Research Institute of Oilseeds and other scientific institutions, when N60-90P90 is applied, the seed yield increases by 16-20%. Recommended application rates for mineral fertilizers N20-40P40-80K40-60 (Kolomeichenko). According to other recommendations, P80-90K80-90, which are applied under autumn tillage, and N90 – in spring (Niklyaev).

Phosphorus fertilizers give a greater effect on chernozem soils, nitrogen fertilizers on gray soils.

Also high efficiency gives pre-sowing introduction of granulated superphosphate in doses of 10-20 kg/ha P2O5. In the conditions of the Stavropol Territory, the introduction of ammophos into rows is effective when sown at the rate of 60 kg/ha.

A good effect is given by top dressing during the growing season with nitrogen, phosphorus and organic fertilizers in 1-2 stages. If the main fertilizer was not applied, then top dressing is recommended to be carried out before the first inter-row cultivation. If the main fertilizer was applied, then top dressing is carried out a little later – at the beginning of the formation of the central brush. For top dressing, you can use ammonium nitrate, ammonium sulfate and superphosphate. From local organic fertilizers for the same purposes – bird droppings and slurry. Top dressing at the rate of N20P20 should be applied to the moist soil layer to a depth of 8-10 cm.

Tillage system

Soil cultivation for castor beans includes:

  • peeling following the harvesting of previous cereal crops;
  • plowing in August to a depth of 27-30 cm with plows with skimmers;
  • snow retention;
  • early spring harrowing and sanding;
  • 2-3 cultivations with harrowing.

According to the results of All-Russian Research Institute of Oilseeds experiments carried out in the Krasnodar Territory in areas prone to dust storms, flat-cut tillage, including two plowing with flat-cutters and deep nonmoldboard loosening of the soil, is of great positive importance.

Under castor beans, spring chiselling is effective.

To control weeds, the herbicide treflan is used, which is applied to the soil during pre-sowing cultivation at the rate of 6-8 kg/ha according to the preparation.

Sowing

For sowing, varietal, large and leveled seeds are used. The purity of the seed must be at least 98%, germination – at least 85%.

Before sowing, the seeds are treated with granosan with dye (2 kg/t of seeds) or TMTD (4 kg/t of seeds).

Sowing begins when the danger of frost has passed, and the soil at a depth of 10 cm warms up to (10) 12 °C. Early or late sowing leads to a noticeable decrease in seed yield.

Sowing method – dotted with row spacing of 70 cm, using SUPN-8 or SCH-6MF seeders.

The seeding rate for large-seeded varieties is 20-25 kg/ha, for small-seeded varieties – 10-12 kg/ha.

The sowing depth is 6-8 (10) cm and varies depending on the moisture content and mechanical composition of the soil. On heavy soils, a sowing depth of 6-8 cm is recommended, on light sandy soils – 10-12 cm.

Plant density depends on varietal characteristics and growing region and usually ranges from 45 to 60 thousand/ha (Vavilov). According to other data, the recommended plant density for branched varieties is 30-40 thousand/ha, for weakly branched varieties – 50-60 thousand/ha (Kolomeichenko).

Crop care

Care of castor bean crops includes pre-emergence harrowing to break up the soil crust.

In the presence of weeds, inter-row cultivation is carried out.

In the phase of the second true leaf, seedlings are thinned out, leaving the plants in a row at a distance of 35-40 cm from each other.

In the phase of 2-3 true leaves, it is advisable to carry out harrowing by seedlings.

After the emergence of seedlings, the aisles should be kept loose.

An important agricultural technique for castor beans is chasing plants,
which consists in removing the apical point of growth of the main shoot or buds of side branches. It is carried out with the formation of 4-5 true leaves. Chasing the main shoot helps to accelerate the development of brushes on the branches of the first order. If the buds of the lateral shoots are removed, then the development of the central brush improves and maturation accelerates.

In conditions of areas with sufficient moisture and during irrigation, it is advisable to carry out hilling, which reduces the lodging of plants.

Harvest

Ripening of castor bean pods occurs unevenly. First, the boxes ripen on the central brush, then on the brushes of other orders (lateral).

Harvesting requires relatively even maturation and low humidity for most of the pods. Therefore, for these purposes, drying on the vine (desiccation or defoliation) with magnesium chlorate is carried out, when the bolls on the plants are not yet cracked. During aerial spraying, the consumption of the drug is 15 kg/ha per 100 liters of working fluid. Desiccation is performed when the bolls of the central castor bean cluster turn brown, by this time the accumulation of dry matter and oil in the seeds ends. In 1-2 days after the treatment of crops with a desiccant, the leaves dry up, however, the drying of boxes and seeds on the vine occurs in 12-15 days in favorable weather. At this time, they begin harvesting.

Harvesting is carried out single-phase and two-phase. The single-phase method is applicable only for varieties with non-cracking boxes. For this method, a ККС-6 castor-bean harvester is used, which cuts the plants, breaks and splits the boxes, separates the heap and collects the castor seeds in a separate hopper.

With a two-phase method, grain combines equipped with special devices can be used. The resulting heap is immediately dried and cleaned. After that, threshing is carried out on the castor-bean thresher КЩМ-2.

Harvesting of cracking varieties of castor beans is carried out selectively, as the brushes ripen, in 2-3 terms.

Seeds with a moisture content of not more than 6% are laid for storage (Vavilov). According to other sources, no more than 8% (Kolomeichenko).

Sources

Crop production / P.P. Vavilov, V.V. Gritsenko, V.S. Kuznetsov and others; Ed. P.P. Vavilov. – 5th ed., revised. and additional – M.: Agropromizdat, 1986. – 512 p.: ill. – (Textbook and textbooks for higher educational institutions).

V.V. Kolomeichenko. Crop production / Textbook. — M.: Agrobusinesscenter, 2007. — 600 p. ISBN 978-5-902792-11-6.

Fundamentals of agricultural production technology. Agriculture and crop production. Ed. V.S. Niklyaev. – M .: “Epic”, 2000. – 555 p.