In this essay we will discuss about:- 1. Origin and Distribution of Castor 2. Area and Production of Castor 3. Climate, Soils and Tillage 4. General Characteristics 5. Varieties and Seasons 6. Seeds and Seeding 7. Nutrient Management 8. Cropping Systems 9. Water Management 10. Weed Management 11. Harvesting 12. Quality Consideration.
Contents:
- Origin and Distribution of Castor
- Area and Production of Castor
- Climate, Soils and Tillage of Castor
- General Characteristics of Castor Plant
- Varieties and Seasons of Castor
- Seeds and Seeding of Castor
- Nutrient Management for Castor
- Cropping Systems of Castor
- Water Management for Castor
- Weed Management for Castor
- Harvesting of Castor
- Quality Consideration of Castor
1. Origin and Distribution of Castor:
The origin of castor is obscured by its wide dissemination and spread in ancient times. Castor is indigenous to eastern Africa, especially Ethiopia but elsewhere there is considerable evidence indicating its introduction. According to De Candolle (1890), tropical Africa is the original home of castor.
Castor (Ricinus communis), known as erand in Hindi, diveligo in Gujarati and amudam in Telugu plays an important role in countries’ vegetable oil economy. Today, castor oil finds application in the manufacture of a wide range of ever expanding industrial products.
Apart from meeting the internal demands, India exports annually about 150 thousand metric tonnes of castor oil worth around Rs300 crores in foreign exchange. At present, India ranks first in the world in terms of area, production and productivity.
However, according to Vavilov (1949), Ethiopia is the centre of origin of Castor. It can reasonably be assumed from the available literature that castor is infact indigenous to east Africa and most probably originated in Ethiopia.
Major castor growing countries are India, Brazil, China, Argentina, USA, Thailand, Queensland, Egypt and Sudan. In India, important states producing castor are Andhra Pradesh, Gujarat and to some extent Tamil Nadu, Karnataka, Orissa, Madhya Pradesh and Bihar.
2. Area and Production of Castor:
Globally, castor constitutes less than one per cent of total oilseeds production. In recent times, India has quadrupled the production while China has doubled its castor production. Total area under castor (2003) in the world was about 1.16 M ha with an annual production of around 1.14 M t. The world’s average productivity was around 983 kg ha-1. India ranks first both in area and production with an average productivity of 1146 kg ha-1 as against world average of 983 kg ha-1.
In India, the area under castor gradually decreased from 0.8 M ha in 1990 to 0.7 by 2000 and again gradually increased to 0.73 by 2009-10. In spite of fluctuations in caster area under cultivation, production increased due to increase in productivity from around 800 kg ha-1 in 1990 to 1372 kg ha-1 in 2009-10.
On an average, Gujarat alone produces about 80 per cent of total castor of our country from around 50 per cent of the area with a record productivity around 2000 kg ha-1. Other important castor producing states are AP, Rajasthan, Karnataka, TN and Orissa.
3. Climate, Soils and Tillage of Castor:
Climate:
Castor, although basically a warm region crop, grows in temperate and tropical regions throughout the world and it is difficult to define those most suitable for its development. It can be successfully grown from 300 to 1800 m above sea level.
Latitude and Altitude:
Castor production lies between 40°N and 40°S. It can grow well at sea level and naturally growing at an altitude of 2750 m near equator. In India, it is successfully grown up to 1500 m.
Temperature:
Castor requires moderately high temperature of 20°-26°C with low humility throughout the growing season for maximum yields. Low temperature extends the emergence, rendering the emerging seedlings liable to attack by fungal diseases and insects. High temperature at flowering (around 41°C) for even short period results in blasting of flowers and poor pod set. A frost free growing period between 130 to 190 days, depending on cultivar, is necessary for satisfactory yields, particularly from dwarf hybrids.
Day Length:
Basically, a long day plant, castor is adaptable to, with some loss of yield, to a fairly wide range of day lengths from 12 to 18 hrs.
Rainfall:
With a reputation for drought resistance, castor nevertheless, produces highest yields with a minimum rainfall between 600 to 760 mm. For optimum growth and development, approximately 100 mm evenly distributed rainfall in each of the first four months period is desirable. There should be no shortage during flowering period.
Soils:
Castor will grow on any type of soil but well drained sandy loams will produce optimum yields. The crop is sensitive to excess soil moisture. In India, it is grown on sandy loams and shallow black soils of Andhra Pradesh and deep sandy loams of Gujarat and Rajasthan. Castor prefers soils of slight acidity (pH 5.0 to 6.5) but can grow up to pH 8. Extremely fertile soil favours excessive vegetative growth at the expense of seed yield.
Tillage:
The type of seedbed required for castor is, generally, similar to that prepared for maize and cotton. For even germination, castor requires a moist soil over a longer period over maize and cotton.
Land should be ploughed immediately after pre-monsoon showers followed by harrowing after each rain. Summer ploughing helps to break open hard soil pans, especially shallow soils. Adequate slope may be provided to avoid waterlogging.
4. General Characteristics of Castor Plant:
The plant varies greatly in its growth habit, colour of foliage and stem, seed size, colour and oil content so that cultivars often bear little resemblance to each other. Some are large perennials often developing into small trees, others behave as short-lived dwarf annuals and every graduation between these extremes can be found.
Root, Stem and Leaf:
Main taproot of castor grows several meters long with secondary ones restricted to about 75 cm of soil depth. The tertiary roots are very long up to more than 45 cm. Root hairs are usually absent.
The stem is cylindrical, glabrous, frequently glaucos with a woody hollow center and stem colours varying from bright green, green with reddish bluish, carmine or rose red etc. The stem is marked by a number of nodes, which are close at base and distinct in upper portion.
Leaves may have wide range of foliage colours and size. Leaves are simple and palmate with 7 to 11 lobes. Waxy bluish bloom may present in certains.
Inflorescence:
Inflorescences are born on the main, lateral and tertiary branches. The main stem is terminated by an inflorescence or raceme, known as primary and is usually the largest on the plant. The inflorescence is also known as candle or spike and consists of fairly close panicles of unisexual flowers in clusters of three or four arising spirally on the raceme axis.
The male flowers (staminates) occur in groups at the base of the inflorescence and the female flowers (pistilates) are born on the upper part. Flowering occurs from the base upwards.
Staminate flowers usually open simultaneously with pistilate and desiccate after pollen discharge. Pollen is shed readily between 26° and 29°C, with relative humidity of 60 per cent. A temperature of 15°C delays shedding.
The plant produce flowers over an extended period. The lowest flowering raceme on the plant is usually to first to mature but the upper and latest racems may be just beginning to flower at the end of growing season of cultivated annual cultivars.
5. Varieties and Seasons of Castor:
Varieties:
Breakthrough in varietal front was achieved in late 1960s with the development of Aruna, a short duration (120-150 days) mutant. Until the advent of Aruna, long duration varieties (220-280 days) were under cultivation. Subsequently two more short duration varieties Bhagya and Sowbhagya were released. Importance of hybrid vigour was commercially exploited in castor by the release of GCH 3.
Unfortunately, it was not accepted due to shattering quality. Subsequently, GAUCH 1 hybrid, which completely replaced the earlier one, possesses more efficient root system to yield better under dryland conditions. Hybrids GCH 1 and GCH 2 became popular in all castor growing areas.
Improved cultivars under cultivation are given in Table 17.1:
Seasons:
In India, castor is essentially a rainfed crop during kharif. Seeding time depends on the onset of monsoon. Early sowing results in high yield. However, early sown crop suffers from severe incidence of semilooper.
Availability of short duration varieties and hybrids and improved management practices have now made rabi and summer cropping possible under irrigation. The area and irrigated castor is gradually increasing, particularly in Andhra Pradesh and Gujarat.
6. Seeds and Seeding of Castor:
The seeds may be treated with Thiram or Bavestin (3 g kg-1) to protect from seed born alternaria blight, seedling blight and wilt.
Time of Seeding:
The most ideal time for seeding kharif castor is immediately after the receipt of monsoon rains. Recommended seeding time for rainfed castor in Andhra Pradesh is second fortnight of June and in Gujarat first fortnight of July. Although, no precise information is available on optimum planting time for rabi and summer castor for different regions, preliminary information suggests September- October and January as ideal periods respectively.
Seed Rate and Spacing:
A plant population of 55,000 ha-1 has been found optimum for rainfed castor in the entire castor growing regions of the country. For achieving required plant stand, a seed rate of 6 to 8 kg ha-1 is adequate depending on seed size. For an irrigated crop, optimum plant stand is 18,500 plants ha-1 and the recommended seed rate is 5 to 6 kg ha-1.
Closer spacing results in increased plant height and duration, delayed flowering and reduced branching and wider spacing encourage heavy weed infestation. Recommended spacings in different regions and situations are given in Table 17.2.
In case planting is delayed for want of timely rains, a closer spacing of 60 x 15 cm instead of 90 x 20 or 60 x 30 cm is ideal to curtail excessive vegetative growth.
Method of Seeding:
In southern part of the country, the seed is generally sown (2 at a place) in plough furrow behind traditional plough in moist zone 10-12 cm below the soil surface. The seed is dropped by hand and covered by running a light plank. Use of fertiseed drill, preferably, with a wider row spacing of 90 cm facilitates larger area coverage under rainfed conditions. Dibbling the seed either in flat bed or at the base of ridge is common under irrigated conditions. Only on healthy seedling is stained 20 DAS.
7. Nutrient Management for Castor:
Castor crop grows well on a variety of soils with variable fertility. Thus, the fertiliser requirements vary depending on the environment in which the crop is grown. A crop yielding 2000 kg seed and 1,333 kg hulls removes around 80 N, 18 P2O5, 32 K2O, 12 Ca and 10 Mg kg ha-1.
Nitrogen:
Nitrogen application is frequently related to available soil moisture through rain or irrigation. In Telangana region of Andhra Pradesh, farmers usually apply around 5 t FYM ha-1 once in 2-3 years for traditional varieties. However, for improved varieties, around 50 kg N ha-1 is the usual rate of application now a days.
In northern parts of the country, around 60 kg N ha-1 is applied along with phosphorus. At Coimbatore (TN), about 40 kg N ha-1 along with 5 t ha-1 of FYM appears to be economical. In general, response of castor to nitrogen increases with increasing levels of phosphorus and potassium.
Introduction of improved varieties and hybrids, especially under irrigation, completely changed the farmer’s attitude towards fertiliser use in castor production. Depending on the level of management practices, recommended rate of nitrogen ranges from 90 to 140 kg ha-1 under rainfed conditions.
However, applications beyond 100 kg N ha-1 are not economical in most rainfed conditions. Under irrigation, application up to200 kg N ha-1 is not uncommon, especially for hybrids in Andhra Pradesh and Gujarat.
Phosphorus:
Fixation of applied phosphorus in soils and its applications annually for economic castor production. Basal application around 30 kg P2O5 ha-1 is considered adequate under rainfed conditions in India.
Results of experiments clearly indicated the necessity for phosphorus applicant in different parts of the country. In north India, phosphorus alone has no significant effect in increasing the castor yield. Economic yields can be achieved with about 30 kg P2O5 ha-1 along with 60 kg N ha-1. A similar response to phosphorus has been reported from Andhra Pradesh. Improved cultivars are responding up to 75 kg P2O5 ha-1, when nitrogen is not a limiting nutrient.
Potassium:
Many tropical soils are well supplied with available potassium but application of nitrogen and phosphorus may result in increased uptake of potassium. Additional potassium may then be required to maintain the nutrient balance necessary for optimum castor yield. Response of caster to potassium is not common in India. However, maximum yields are obtained only when potassium is applied along with nitrogen and phosphorus.
Recommended fertiliser schedule for different states and situations is given in Table 17.3:
Time and Method of Application:
For a rainfed castor crop, general recommended fertiliser schedule is 60 N and 40 P2O5 kg ha-1. Nitrogen must be applied in three split doses, 20 N each at sowing, 35-40 and 65-70 DAS. Recommended phosphorus must be applied as basal dose at sowing along with 20 kg N. Deep placement of fertiliser 5 to 7 cm below the seed and 10 cm away from the seed row is preferred. In the event of dry spell during first 50-55 days, first nitrogen top dressing should be at the time of initiation of secondaries as and when rains are received.
For an irrigated crop around 180 days duration, recommended fertiliser schedule is 120 N, 40 P2O5 and 40 K2O kg ha-1. As a basal dose, 40 kg N along with recommended dose of phosphorus and potassium must be applied by placement at sowing. The remaining nitrogen (80 kg) must be applied in four splints of 20 kg each at 40, 70,100 and 135 DAS.
Alternately, 40 Kg N must be applied as basal dose along with phosphorus and potassium at sowing. Top dressing of nitrogen must be at the rate of 20 N kg ha-1 at each successive picking, starting from 90 DAS or harvest of first order spike at intervals of 30 days. Depending on the number of pickings, nitrogen dose may be even higher than the general recommended rate of 120 kg ha-1.
In Andhra Pradesh, recommended fertiliser schedule for improved varieties is 60 kg N ha-1 in three splits (50% basal and the remaining in two equal splits at 30 and 60 DAS) and for hybrids, 80 kg N ha-1 in three splits (1/2 at seeding and the remaining in two equal splits at 30-35 and 95 DAS). For both varieties and hybrids, phosphorus and potassium are recommended at the same rate of 40 and 30 kg ha-1 respectively as basal application.
Response of castor crop to secondary and micronutrients is not common. Application of single superphosphate as the source of phosphorus is adequate to meet the sulphur needs of castor. Castor crop is a poor extractor of zinc. Soil application of 25 kg Zn SO4 ha-1 once in 2-3 years can meet the castor needs under rainfed conditions. In intensive irrigated cropping systems, application of zinc to other crops in the system can meet the needs of castor.
8. Cropping Systems of Castor:
Castor crop is usually cultivated either as a sale crop or intercrop with cereals and grain legumes and in some cases with commercial crops such as chillies, turmeric etc. as border crop.
Intercropping:
Viable intercropping systems recommended for different rainfed regions in the country are given in Table 17.4.
Sequence Cropping:
Castor is usually a full season year crop. However, under intensive irrigated cropping systems, there is scope for sequence cropping.
Usual one year crop sequences under rainfed situations are:
Sorghum-castor
Pearlmillet-castor
Castor-pigeonpea
Castor-groundnut
Castor-cotton
There is scope for a short duration sequence crop of castor on store soil moisture, especially on black soils after a short duration pulse crop. Under irrigated conditions, castor crop can be grown during rabi after kharif rice from January to June.
Nipping:
Nipping is removal of all auxiliary buds as and when they emerge. This technique is preferred in intensive cultivation of seed plots and also when castor is grown as an off-season crop. The primary raceme first appears in the form of a bud and develops in about 10 to 15 days. Nipping facilitates synchronous flowering and capsule development and therefore, helps in easy harvest besides reducing maturity period in intensive cropping systems under irrigation.
9. Water Management for Castor:
Castor is usually a rainfed crop. However, it responds well to irrigation. If one or two irrigations are given during drought spells, castor yields can be doubled.
Critical Stages for Irrigation:
Supplemental irrigation for rainfed crop, if drought persists, must be given at primary spike development or secondary spike initiation. Flowering and seed development stages are considered critical stages for irrigation.
Scheduling Irrigation:
Information of scheduling irrigation and water requirement of caster is limited. From the available information it is evident that castor can absorb moisture from deeper layers due to its deep root system. As such, it is desirable to give relatively heavy irrigations at longer intervals than frequent irrigations.
For rabi castor, first irrigation must be given around 50 days after seeding or around full flowering of primary spike. Subsequently, irrigations may be given at an interval of 20 days. In all, a crop of 180 days duration require around 6 irrigations for optimum yield.
Depending on soil type and weather during the crop season, castor crop needs 500 to 700 mm water for optimum yield with water use efficacy of 1.0 to 1.5 kg ha-1 mm-1 of water. As castor is sensitive to waterlogging at all the stages of growth, it is desirable to irrigate the crop following the furrow method of surface irrigation to drain the excess water.
10. Weed Management for Castor:
The wide row spacing and initial slow growing nature of the crop is ideal for weed growth. Critical period of weed competition is first 20 to 60 days after seeding.
Cultural Management:
In rainfed castor crop, two or three intercultivations with bullock drawn blade harrows, starting from 20 DAS along with a manual weeding within the row can effectively check the weed growth. Square planting is adopted in certain areas of Andhra Pradesh to run the blade in both the directions for effective weed control.
In irrigated castor, 2 to 3 hand weedings at an interval of 15 days, starting 15 DAS can check the weed growth effectively. Alternately, herbicides may be used against the weeds.
Use of Herbicides:
Several herbicides are available for weed control in castor. Use of herbicides may be economical in irrigated castor. Any of the following herbicides are effective in castor crop.
Package of Production Practices:
Summary of major cultural practices for castor production are presented as package of production practices for castor crop.
Tillage:
1. Two to three ploughings followed by harrowing would be adequate for timely sowing.
2. Deep ploughing aids in perennial weed management besides conserving soil moisture.
3. Adequate grade has to be provided for draining excess water to prevent waterlogging.
Varieties for AP:
1. Hybrids: GCH 519, PCH 1, DCH 117.
2. Varieties: Haritha (PCS 124), Kiran (PCS 136), Jwala.
Seeds and Seeding:
1. Optimum seeding time for AP, TN and Karnataka is second fortnight of June, Gujarat and Rajasthan first fortnight of July, Haryana second fortnight of July and AP, TN, Karnataka, Orissa (rabi) September-October
2. For rainfed crop, spacing varies from 90 x 60 to 120 x 60 cm and for irrigated crop from 90 x 60 to 60 x 60 cm.
3. Seed is dropped in plough furrows behind country plough at about 10-12 cm soil depth.
4. Seed rate is 6-8 kg ha-1 for rainfed and 5-6 kg ha-1 for an irrigated crop.
Fertiliser Schedule in AP:
1. Recommended NPK rate for rainfed varieties is 60 + 40 + 30 and for rainfed hybrids 80 + 40 + 30 kg ha-1.
2. For rainfed varieties, apply half N and entire P and K at sowing and ¼ N at 30-35 DAS and ¼ N at 60-65 DAS .by drilling/placement.
3. For rainfed hybrids, apply half N and entire P and K at sowing and ¼ N at 30-35 DAS and ¼ N at 90-95 DAS .by drilling/placement.
4. For irrigated hybrids, recommended dose is 120+40+40. Apply 40 N along with entire P and K at sowing by drilling/placement Remaining N in four equal splits at 40, 70, 100 and 135 DAS by placement.
Water Management:
1. Flowering and seed development are critical stages for irrigation.
2. First irrigation around 50 DAS or full flowering of primary spike.
3. Subsequent five irrigations at 20 days interval.
Weed Management:
1. First 20-60 DAS are critical stages for weed competition.
2. Two to three intercultivations starting from 20 DAS followed by a manual weeding would be optimum under several situations.
3. PRE Pendimethalin, Nitrofen and Alachlor or PPI Flucholarin, Trifluralin and Neptalam can effectively control the weeds.
4. Integrated weed management involving land preparation, intercultivation and herbicides appears to be ideal if soil moisture is not a limiting factor.
11. Harvesting of Castor:
Harvesting:
On an average, castor plant produces 4 to 5 sequential order spikes over a span of 180 to 240 days, one each at an interval of 30 days. The main spick is ready for harvest within 100 days after seeding. Subsequent harvests can be at intervals of 30 days in the case of improved cultivars.
Premature harvesting as soon as the capsules turn yellow must be avoided. Such a practice reduces seed weight besides lowering the oil content. Optimum stage for harvest is capsules turning yellow and starts drying.
Threshing:
Harvested spikes are usually placed in heaps around a week and then sun dried for a couple of days. Threshing is usually done by either beating the well dried capsules with sticks or trampling under the feed of cattle or tractor. Of late, power operated mechanical threshers are used for threshing large quantities of capsules. Castor seed can be stored safely in gunny bags without loss for over three years.
12. Quality Considerations of Castor:
Seed Composition and Oil Quality:
Oil content of castor seed ranges from 40 to 55 per cent. It contains 12-16 per cent protein, 2-7 per cent carbohydrates and 23-27 per cent fibre. Dehulled seed contains 60 to 70 per cent oil and 18-26 per cent proteins.
Castor oil is unique, in that it contains 85 to 90 per cent resinoleic acid. The hydroxy group of recinoleic acid imparts a very high degree of viscosity and oxidative stability, which is four times more stable than olive oil.
Castor cake contains 6 per cent nitrogen, 2.5 per cent phosphorus and 1.5 per cent potassium. As it contains toxic constituents, it is unfit for edible purpose. Except to poultry, it cannot be fed to any other animals. Hence, castor cake is mainly used as organic manure.
Toxic Constituents:
Castor seed contains an alkaloid recinine, which is mildly toxic and a protein, which is extremely poisonous. It also contains a heat stable allergin, which is irritating to humans. All these toxins in the cake do not get extracted into the oil.
Uses of Castor Oil:
Castor oil is mainly used as a lubricant because of its property to remain liquid even at very low temperatures (-32°C), high density and viscosity. It occupies a pride of place with coconut and sesame oils as hair oil.
Oil is used in treatment of eye inflammation. It finds use in the treatment of guinea worm abscess and flatulence. The major outlet for castor oil in India is in soap making and to a smaller extent in paints and varnishes.