Oilseed
National Oil Seeds Research and Development Programme
Introduction
The National Oil Seeds Research and Development Programme was initiated in 1972 and was mandated to develop oilseeds which at that time included groundnuts, soyabean and cotton besides sunflower. To date, from the initial crops, only sunflower remains as the other crops went to their respective teams food legumes and fibre. To compensate for the loss, new oilseed crops that include Castor, Jatropha, Safflower and Sesame were introduced in the programme. The programme has another introduction Artemisia annua L.
Objectives
The main objectives of the National Oilseeds Research Programme are;
- To contribute towards the attainment of self-sufficiency in oilseeds production with a view to export by providing crops that are suitable and acceptable for production by a wide range of farmers in Zambia.
- To assist in the promotion of crops which can easily be processed in the areas of production and hence add value.
- To continue looking and developing crops that will compete favourably both at local and international markets.
Nature and Content of Research
The research being carried out on oilseeds include germplasm collection from both local and exotic sources for the purpose of population development and hybrid seed production in the case of sunflower. Current research concentrates on sunflower with some effort being put on the industrial oilseed crops of castor and Jatropha. The other crops, safflower and sesame has minor attention. In this regard, active research is under way in the areas of breeding, agronomy, seed purification, multiplication and maintenance.
Major Achievements in the Programme
The National Oilseeds Development Programme has been among the research programmes that have been successful at developing and releasing new varieties. However, all the varieties released only come from its major crop Sunflower. The programme has in this respect released 5 hybrids and 4 composites. The hybrids released include;
• CH258
• CH284
• CH301
• CH336
• CH311
In composites category varieties released include
• CCA74
• CCA81
• SAONA
• MILIKA.
It is hoped that with more attention a variety each from the other crops will also be achieved.The programme offers advisory services for all crops in terms of production recommendations which have been prepared as leaflets and gets updated as soon as new information is acquired.
Brief Description and Production Guide of Mandate Crops
Following is a brief description and production requirements of mandate crops.
Sunflower (Helianthus annuus L)
Many households cannot do without edible oils for cooking. While there are a number of crops that can supply edible cooking oils, sunflower stands out as one of the best sources in Zambia. The country stands to save much money importing vegetable oils if much attention could be directed at growing sunflower. It is a crop that can give an economical yield with minimal use of inputs particularly inorganic fertilisers when grown following a good managed cereal like maize. The crop is suitable for production by all categories of farmers and can be processed right at the farm. Sunflower is currently grown in all parts of the country and yields obtained are very low. The main causes of the low yields are late planting, high weed competition, use of poor quality seed and poor methods of planting.
Generally, sunflower yields decline an average of 15% for each 2 weeks delay beyond recommended planting dates. Late planted sunflower crops also lose 5-10% in oil content.
Weed competition during the first 4 weeks after emergence could cause 10-15% yield loss. If weeding is delayed for 6 weeks, yield reduction could range from 15 to 30%. Like wise, a delay of 8 weeks after emergence could reduce the yield by 25-50%. No weeding at all could result in yield losses of 30-75%. Use of poor seed also contributes to poor yields. Broadcast seed makes it difficult to achieve a proper plant population that contributes to low yield. Broadcast seeding also makes it hard to weed and fertiliser the crop.
There are 2 sunflower types available, hybrids and open pollinated. The hybrids released include; CH258, CH284(Monde), CH301(Phindu), CH336(Mutinta) and CH311(Kayula). In composites category varieties released include; CCA74, CCA81, SAONA and MILIKA. Seed from a previous crop from open pollinated varieties can be used for 1-2 years, hybrid seed must be purchased every year. However, it pays to grow hybrids since they yield on average 30% more than open pollinated varieties. Soils good for maize are good for sunflower.
While sunflower is relatively drought tolerant and do well in the drier areas, the present varieties require adequate soil moisture approximately for 3 months after germination, for optimum grain yields and oil content. Fields where sunflower is to be planted should be well ploughed and using a rope mark out straight rows, certified seed should be planted in shallow furrows along the rope using a hoe. The furrows should be 2 to 5cm deep. Alternatively, an ox or tractor cultivator can be used to mark shallow furrows. Ploughing furrows should not be used for planting sunflower as these are likely to be too deep. Seed rate of 5-8kg/ha should be adequate and seeds should not be covered with big lumps of soil.
Weed control for first 4 weeks in a sunflower crop is essential for top yields. The effective weed control programme for sunflower for those who can afford is the use of a grass herbicide at planting and one cultivation before 8 leaf stage. Alternatively, 2 timely mechanical weedings should provide adequate weed control.
Fertiliser and lime to be applied according to soil test results. Average fertiliser application on well fertilised rotated lands is 200 kg/ha D or X as basal and 100kg/ha of either Urea or Ammonium Nitrate as top dressing.
The main diseases experienced in sunflower are leaf spot and leaf blotch and these are controlled by varietal resistance. Cut worms may attack the crop at seedling stage and spraying using Dursban @ 1.5litres/ha or 150ml/15litre sprayer should be done at first sign of damage. If Nysius bur or caterppilar populations are high, spraying with thiodan @ 2kg/ha will control the pests. It is however, very important to remember never to spray the crop once flowering has started as this will kill bees which are necessary for pollination.
When the backs of sunflower heads have turned yellow and sunflower bracts start getting brown, the heads can be cut with a knife and placed upside down on their stalks(stems). Spiking helps in reducing yield losses caused by bird damage and shattering and also ensures uniform drying. If spiking is not done, bird scaring prior to harvesting may be needed to minimise seed loss. Both head and bracts should have turned brown before harvesting. The sunflower grain should be dried well before bagging.
Sunflower can be rotated with maize, sorghum, wheat cotton, groundnuts and soyabean. If it is established that the field is infested with nematodes avoid rotation with soyabean, tobacco, potatoes and tomatoes in close succession rotation.
Castor (Ricinus communis L)
Castor is a source of industrial but essential oils. In Zambia castor grows wildly all a cross the agro-ecological zones and is not a difficult crop to grow. The seed of castor may contain up to 50% oil that can be easily expressed using hand held machines such as the ram and spindle presses. The crop attracts a good price internationally and the market appears to be favourable. Despite all the potential that castor commands, very little is going on in terms of local production.
Castor prefers medium to light soils which are well drained. Castor also prefers soil of pH of 5 to 6 just as for maize and cotton. Minimum tillage with Magoye ripper is preferable. Castor cannot stand water lodging even for one week.
Castor should be planted at a time so that it will flower when there are light rains with low humidity. Heavy rain or dew usually trigger fungal [moulds] attacks to the flowers which can greatly reduce yields.
Thoroughly treat the seed before planting with a fungicidal seed dressing (such as Thiram]which protect seedlings from blights. Seed could also be treated with Molybdenum to avoid any yield loss due to this trace element deficiency in the Zambian soils.
Spacing for Misacas should be 1m between rows and 50 centimetres between plants with direct seeding. For first year ratooned crop, it should be 1metre between rows and 1metre between plants.
One seed at each planting station should be planted 5 to 8 cm deep for best results. If seed cost and quantity are not limiting, plant two seeds per station and then thin back to 1, one week after emergence. This will ensure that you get optimum plant population per area which in turn means higher yields.
Castor seed germinates slowly – from 8 to 30 days. Therefore, plant when there is ample moisture in the soil.
Castor can be grown without any fertilizer if it follows [in rotation] a crop which was well fertilized or good quality virgin soil. On poor soils, about 200 kg [the more plants per area, the more fertilizer that needs to be applied] of D or X Compound should be applied to a hectare of castor crop to get good yields.
Castor field should be kept weed free during the first one and half months of growth period. Weeds can be controlled either by mechanical means such as shallow hand hoeing or by applying herbicides such as Treflan and prowl.
Generally speaking, castor is susceptible to the same insects as cotton. Cutworm is a big problem when castor is grown after maize. For control, spray Karate soon after emergence, 100ml/ 250 litres of water per hectare.
Sucking insects and stink bugs should be controlled by spraying the crop with Carbanyl or with Malathion 25 WP as per manufacture’s instructions.
Seedling blight (phytophthora Colocasiae) occurs in dump and low lying areas. For treatment, see under seed preparation paragraph. Alternaria blight (Alternaria ricini) and bacterial leaf spot (Xanthomonas ricinida) also occurs in the country.
To prevent fungus (moulds) from greatly reducing the yields, Copper Oxychloride must be applied at a rate of 400 g/100 litre of water per hectare at first flowering and second flowering. If necessary, spray at 3rd and 4th flowering.
Misacas 3 variety, being a perennial cultivar will bear ripe fruit about 180 days (6 months) after sowing.
Capsules can be stripped off the raceme wearing cloth gloves. Using a stripping cup, one worker should harvest 150-300 kg capsules daily.
First year yields are generally less than a tonne per hectare, while second year (ratoon trees in November) yields of at least 1 tonne per hectare can be expected.
Storage on-farm of large quantities of castor grain should be avoided whenever possible for seed are large and occupy considerable space in relation to their weight. Castor grain should not be stored in the open except for short periods as heat and sunlight reduce the oil content and quality.
Sesame (Sesamum indicum L)
Sesame is a crop that is generally grown by small-scale farmers and on extremely small plots of land. The crop is reportedly grown in several districts of Zambia with the largest production coming from North-Western Province and in the valleys of Regions I and II. The other areas where the crop is grown include Muyombe, Isoka, Mansa, Mfuwe, Gwembe, Chiawa, Mumbwa and Mukonchi. Sesame seed is an important source of high quality odourless vegetable oil that can be substituted for olive oil and used in the manufacture of compound cooking fat, margarine and salad oils. Lower grade oil is used as a fixative in the perfumery industry, in various cosmetics and as a carrier for fat soluble substances in pharmaceuticals such as penicillin and in insecticides. Sesame oil is easier to extract at village level than is sunflower. No improved variety is available, all production is based on local landraces.
Sesame is a tropical plant but grows in subtropical and warm temperate regions. It is a short day plant and will flower in about 45 days under 10 hour day length. Most varieties are day neutral that grow and flower normally under days of 12hrs or less. Depending on cultivar, the crop matures in 75-150 days after sowing.
Although sesame is considered a crop of the tropics, heavy rainfall and high humidity are detrimental as they increase the incidence of fungal diseases that lower yields. The crop is also susceptible to water logging even for short periods. Heavy rains or prolonged rains after sowing may wash away most of the seeds or cap the soil surface thus preventing seedling emergence. A good crop can be grown with rainfall in the range of 500 mm to 650 mm with a dry period during the ripening time.
Sesame performs well when grown in temperatures of 20-240 C in the early stages while fruiting is favoured by average temperatures of around 270 C. Germination and seedling growth will be delayed when soil temperature is below 200C and inhibited at 100C.
Sesame can grow on a variety of soils provided rainfall is moderate. Best soils are light, sandy loam soils, and well drained but capable of adequate water retention.
Sesame does not do well in water logged, acid soils or shallow soils with impervious sub-soils. Sesame has a very low salt tolerance.
Sesame seed is small seed hence requires a fine, weed free seed-bed which is ploughed to a depth of 10 cm to 20 cm. Uniform depth and seed rate are essential for stand establishment resulting in maximum yield.
Seed rate is between 2 Kg/ ha to 11 Kg/ ha. Higher rates are used when seed is broadcasted as is done by traditional growers. It is recommended to sow densely and thin the plants at the height of 15cm. Plant populations of between 150,000-200,000 are ideal.
Planting earlier than January increases oil content. However, planting too early may result in capsules maturing during wet periods.
Seeds can be broadcasted or drilled in rows. It can be planted by hand or mechanically.
When Sesame is grown by traditional farmers, the seed is mixed seed with those of major crop staple crops such as millet, sorghum or cowpeas. This method makes it difficult to weed and harvest Sesame. With this kind of planting, yields of sesame are generally low.
Planting in rows saves seed. Sesame can be drilled in a wide range of spacings between rows [18 cm to 90 cm], depending on the number of branches the cultivar has. The higher the number of branches the wider the spacing should be. Similarly, spacing between plants within a row ranges between 5 to 25 cm.
The fertiliser requirements of sesame are similar to that of millet;[ 60kg N, 20 kg P 2 O5, and 20 kg K] per hectare. Higher rates of nitrogen reduce seed oil content. Protein is favoured over oil as Nitrogen supply to the seed is increased.
During the initial stages of growth, sesame is a poor competitor with weeds. A weed free seed-bed is recommended since cultivation in a sesame field is not easy. The fine fibrous roots are easily damaged. Row planting allows shallow inter-row cultivation. Pre-planting herbicides such as treflan can be used to control grass.
The major diseases are leaf spots, especially under heavy rainfall and humidity. The other common diseases are: Fusarium wilt, bacterial wilt especially when the crop is irrigated, southern blight, charcoal rot, cotton root rot, and phyllody virus which produces almost sterile plants.
The crop is harvested when leaves begin to shed, the lower capsules turn from green to yellow and the lowest capsules begins to open. In Africa, average yields range from 300-500kg/ha in pure stands. Under good management, yields can be as high as 3,000kg/ha. A yield of 2,000kg/ha is considered necessary for profitable commercial production. In Zambia, yields obtained is 200kg/ha due to lack of improved varieties and losses due to capsule shattering.
Safflower (Carthamus tinctorius L)
Safflower is an important oil crop mostly grown in the drier zones of the tropics that has been found suitable for Zambia. Safflower oil has uses both edible as well as industrial. As an edible oil, safflower has a very high level of linoleic acid that human bodies requires for good health. Industrially, it is a drying oil and is used in varnishes, lacquers, pastel paints and alkyd resins where colour retention is important. Our rainfall pattern in the country is becoming increasingly unpredictable such that it has become necessary to look for new crops to replace the ones falling out of favour. In this respect safflower has been identified as one of the potential crops to try and develop. No improved variety is currently available all seed used in production has to be imported.
Safflower has achenes that are smaller than the better known fruits of the sunflower but have the same shape. They consist of 40-60% by weight of pericarp, 26-37% oil and 20-55% protein. The percentage of oil and protein are very variable because they depend upon the thickness and weight of pericarp. Cultivars with thin pericarp or with achenes which are easily decorticated in processing yield a larger percentage of oil and protein. The oil is used mostly for salads and making margarine. Safflower seed cake is useless as stockfeed unless the fruits have been decorticated because the fibrous pericarps make it unpalatable. Decorticated seed cake contain up to 50% protein.
Industrially, it is a drying oil and is used in varnishes, lacquers, pastel paints and alkyd resins where colour retention is important. The florets contain 0.3-0.6% of scarlet red dye, carthamin which is insoluble in water and about 30% of yellow pigment which is soluble in water and which is removed by washing the dried florets.
Safflower is a member of the Compositae, a large distinctive family of some 20,000 species most of them herbs or shrubs scattered throughout the world. The family include other important crops such as Sunflower (helianthus annuus), Pyrethrum (Chrysanthemum cinerariifolium), Lettuce (Lactuca sativa) and Niger seed (Guizotia abyssinica).
The cultivated plant is an erect annual herb 50-150cm in height with varying degrees of spininess. The tap-root is long and stout with many thin lateral roots which grow more or less horizontally in the upper layer of the soil. Early growth is slow with young plants having a rosette of leaves close to the ground. Later several erect branches grow from leaf axils in the rosette and these in turn give rise to more branches higher up the plant. Branches are stiff, cylindrical and whitish in colour.
The extensive root structure and waxy leaves of safflower make the crop to be tolerant to drought that an economic yield can be obtained with only two good rains after planting. However, for assured yields, the crop should receive somewhere near 500mm rainfall with no long rain-free periods during the growing season. This means farmers can afford to plant safflower in February in Regions 1 and 2 and in March in Region3. This also means it can be grown twice in a year especially with irrigation.
The following are the requirements for its successful production in Zambia.
(a) Safflower is grown from seed, it may be broadcast or planted in rows with a seed rate of between 28-34kg/ha. Growing in rows is recommended for easy management.
(b) Seed is planted by hand or grain drills or adjustable planter units, 2-3cm deep, 45-75cm row to row spacing and within row spacing of 20-25cm up to 40cm depending on branching characteristics. Closer spacing gives higher oil content and yield per unit area.
(c) Control of weeds is important in early stages of growth because of the slow early growth exhibited by the seedlings.
(d) Emerging plants need cool short days (above 40 C) for root growth and the development of the rosette, and higher day time temperatures (between 24 and 32 0 C ) and long days for stem growth and flowering. Too high temperatures over extended periods cause sterility and poor seed set.
(e) High rainfall and humidity are harmful as they encourage disease development. Best yields are achieved when weather is warm and low in humidity especially during the bloom period.
(f) Dry atmosphere is required during and after flowering for proper seed set and high oil content. It is recommended to avoid growing the crop when heavy rains are likely especially around flowering as it adversely affects pollination. Plants may have to be topped as the first buds appear to induce branching.
(g) The crop does best on deep well drained soils and cannot tolerate water-logging. Safflower responds to nitrogen and phosphorus. The soil fertility status should however be determined through soil testing. It should also be noted that, soil depth and soil water storage have been found to be more important than soil fertility at least in the traditional growing areas. Under Zambian conditions, and application of 200kg/ha D placed 5 cm below the seed is recommended.
(h) To avoid disease build up it is recommended for safflower not to be grown after beans, sunflower, mustard and canola.
The usual length of the growing season under favourable conditions is about 120 days but there are varieties that may go to 150 days. Expected yield with good management is about 1,000kg/ha and may be higher with irrigation. The crop does not lodge or shatter and is not subject to bird damage. However, spininess makes harvesting difficult.
For dye production, Safflower florets that contain 2 colouring matters carthamin and safflower yellow, the fully opened florets are gathered every 2-3 days. For oil production, the plants are harvested when fully ripe and the seed is threshed and winnowed. Oil extraction may be by solvent or mechanically done.
Jatropha (Jatropha curcas L)
Jatropha or Physic nut is a native tree/shrub of South America but adaptable to Africa. The plant bears fruit that has high oil of about 50%. It is a large succulent shrub with very soft wood that can grow near to eight (8) metres and be productive for more than fifty (50)years.
Throughout Africa including Zambia, the Jatropha usually grows wild. In tropical countries, it is well known for its medicinal properties and as an oil seed plant. It is also used as live hedge (not browsed by livestock).
The seeds resemble those of castor bean in shape but are usually dark in colour and cannot be used for nutritional purposes as they contain various poisonous compounds. This plant does not compete with conventional food or feed crops for land and water and thus, it could be an ideal choice to make use of the vast land resources that are presently under-utilised.
The oil from Jatropha is a source of a semi drying oil which has been commercially used as a soap oil, a textile lubricant, an illuminant and a medicinal oil. The oil has gained international attention as a substitute for diesel termed Bio-Diesel.
The demand on climate varies with the origin of the plants. However, Jatropha curcus linn can grow well in warm to hot regions with an annual rainfall between 250 and 300 mm. Grows vigorously in damp valleys but not on arid escarpments. It can survive long dry periods without danger by simply casting off leaves. The altitude required for better growth ranges from sea level to 1800 metres. Do not grow Jatropha curcas in areas with low temperatures or even frost. There is no improved variety available all production is being undertaken using seed obtained from varying sources.
Though Jatropha curcas is drought tolerant and survives in poor stony soils except heavy clays, light sand soils are preferred. Do not expect vigorous growth and high yields on poor, exhausted soils.
Jatropha curcas can be propagated through seed or cuttings:
(i) By Seeds
• Direct seeding should be done at the beginning of the rainy season (mid-November to mid-December)
• Plant 1-2 seeds per planting hole, 3 cm deep.
• Space at 20-25 cm within rows if planted as hedge and 250 cm x 250 cm if planted for re-forestation or in plantations.
If growth conditions are ideal, i.e. good soils, sufficient rainfall and warm to hot climate, then extend spacing up to 500 cm x 500 cm to avoid ‘over-shading’ of leaves and over-lapping of branches. Production will increase considerably.
• You can plant seeds in poly bags 2-3 months prior to rainy season and transplant when rains have established.
It takes seeds 8-12 days for them to germinate.
(ii) By Cuttings
• Cuttings should be selected from central trunks and only from Jatropha shrubs older than one year.
• Cuttings should be 3-4 cm in diameter with short inter-nodes of 30-50 cm long.
• Dip all cuttings in ash to prevent termite attacks.
• Store in shady place and not longer than one week.
• Plant cuttings in the middle of the dry season, September to October. By using the same planting distance as for seed, plant cutting 15-20 cm deep. It takes 2-4 weeks for roots to develop.
• Jatropha planted from seed will produce first seed after 2 – 4 years.
• Jatropha propagated from cuttings might start seed production from 6months to 1 year after planting.
Avoid planting of cuttings during the rainy season to prevent root rot.
Control weeds from time of emergence of Jatropha plants up to 40-50 cm of growth if planted as hedge. In plantations, weed regularly and use weeds as mulch.
Termites seem to cause serious damage to cuttings and leaf miners to Jatropha leaves. Leaf spot diseases seem to be another problem. Acaricides, insecticides and fungicides can be used to control this problem.
To stimulate growth, side branch development and seed production, prune older Jatropha shrubs in August/September.
If fruits (pods) turn yellow (seeds are maturing) and finally blackish they are ready for harvest by hand picking or by stick. Some varieties have pods that shatter when exposed to the sun making it easy to shell but some need the use of rollers, sacks and beating, to remove seeds from pods.
Depending on management and variety, the yield of Jatropha curcus L. can go up to 5 tonnes per hectare. Though no exact yield figures are available for Zambia, Jatropha yields reported from West Africa vary between 0.8 to 3 kg/meter of hedge(4 trubs/m). Reports from GTZ Choma puts one single Jatropha trub planted as hedge yielding 0.25 – 0.75 kg of Jatropha seed per year. In plantations, yields of 2 – 2.5 kg of Jatropha seed/tree/year is reported. Thousand seed weight is put at between 700 – 760 gm and approximately 1370 seeds make a kg of seed.
Artemisia annua L
Zambia is on record as a first African country to introduce the newest generation of Artemisinin Class Combined Therapy (ACT) namely rtemether/Lumefantrine(Coartem®) drug national wide as a first line treatment for complicated malaria. Artemisinin, is a secondary plant product that is extracted from Artemisia annua L. which originates from China where it is used as a traditional herbal medicine. Artemisinin is the major ingredient in the manufacture of Coartem®. Artemisinin is on high demand since few countries grow Artemisia annua and further it is grown under prescribed conditions and if the growing conditions are not met, the quality of Artemisinin is compromised and may fail to meet acceptable standards for the manufacture of Coartem®. The current costs of Artemisinin based-drugs (price per dose) are beyond the means of average Zambians that has forced the government to subsidise the cost to meet demand.
The wild plant A. annua is a temperate high altitude plant that does not grow in the tropics and has few leaves and a low content of the active ingredient used in the treatment of malaria. A hybrid named Artemisia annua anamed (A3) has however, been developed and has wide adaptation that permits its cultivation in the tropics. The hybrid has a high content of the active ingredient and is currently grown in Kenya, Uganda, Tanzania, DRC and South Africa. There is therefore potential for Zambia to grow this plant. Successful growing of the plant in Zambia would bring both financial and health benefits to the country. The local production would also help reduce the price of Artemether/Lumefantrine(Coartem®) malaria treatment drugs.
