In Pakistan after cotton, rapeseed-mustard is the second most important source of oil in Pakistan. It is cultivated over an area of 307,000 hectares with annual production of 233,000 tonnes and contribute about 17% to the domestic production of edible oil.
Rapeseed and mustard seed is a rich source of oil and protein. The seed has oil as high as 46-48 percent, Whole seed meal has 43.6 percent protein. Rapeseed meal is an excellent feed for animals.
Canola: Canola is different from rapeseed and it is lower in erucic acid and glucosinolates, which are anti-nutritive and health. Canola type varieties are free of these elements.
Climate: Rapeseed is well adapted in temperate region and requires cool temperature for vegetative and reproductive growth. The growth cycle of rapeseed may be as short as 70 days or long as 380 days. Rapeseed and Mustard grow best under relatively cool temperatures upto flowering. After flowering they can tolerate high temperature, however, more heat and drought stress may result in a reduction of seed size, crop yield and oil contents. Among rape and mustard crops, sarson is the most susceptible to frost injury whereas,’raya’ and taramira are more tolerant to extreme weather condition.
Soil: Rapeseed-mustard can be grown on a wide range of soils including both light and heavy type. Crop can tolerate a variable range of pH from 5.5 to 8.0. However, the most suitable soils are those that are:
– Deep and free from hardpan, allow good taproot development, uniformly textured, allow even establishment.
– Unlikely to crust after rain, so that the seedling can emerge easily.
– Not prompt to water logging, rapeseed will tolerate winter waterlogging. This applies especially to B. campestris.
– Not Acidic with high aluminum and manganese levels.
Seedbed Preparation: Brassica seed must be placed into a firm, moist warm aerated, well-structured seedbed for rapid germination and seedling growth. A good seedbed for rape and mustard should be reasonably levelled, well packed, slightly lumpy and moist within 2-5 cm of the surface. A loose seedbed with large lumps dries out quickly and affects germination adversely. A very fine seedbed is also not suitable, as heavy rains followed by drought may result in crust formation and impede emergence. A comparatively moist seedbed is desired for zaid Kharif crop to obtain a good germination. Wet soils should be avoided. Rapeseed can be established successfully using direct drilling and zero tillage.
For optimum seed bed preparation one mould board plough 30-40 days before planting is required to preserve moisture. At the time of planting 2-3 times cultivator followed by planking is sufficient for seed bed preparation.
Sowing Time: Timing will be influenced by soil, variety/hybrid, temperature and moisture level. The planting schedule for different areas is as follows:
* NWFP: Mid-September to mid October
* Punjab: 1st October to 1st November
* South Punjab: Mid-October to mid November
* Sindh: Mid-October to mid November * * Balochistan: Mid-October to mid November
Seed Rate: Yields are not affected significantly due to varied plant densities. Moderate adjustments in seed rate have little effect on yield. Thin crop stand compensate by extra branching. However, recommended seeding rates is 1.5 to 2.0 kg/acre.
– Lower than normal seed rate will help to reduce lodging and harvest.
– Seed rate above 2.5 kg/acre will result in tall spindly plants prone to lodging.
– Increased seed rate suppresses weed infestation. At NARC, it has been observed that dense crop stand discourages too many branching and crop matures more uniformly which facilitate combining.
Method of Planting: For obtaining higher yield and better crop management, Rapeseed-mustard should be grown in rows. Optimum row spacing is 30 to 45 cm through a grain box of standard wheat sowing equipment by doing required adjustments for row spacing and placement of seed at uniform depth.
The seed box on modern machines can be calibrated to the recommended low seed rate. If this is not possible, mix seed with the fertilizer, seed mixed in this way will only be in contact with the fertilizer for a short period and germination will not be affected. Use this technique with phosphorus fertilizer only, as those compounds containing nitrogen may affect germination.
Sowing Depth: Soil temperature and the availability of surface moisture will influence sowing depth. Drill seed into moist soil to an even, shallow depth of 2 to 4 cm, although seeds are small, the seedlings grow vigorously and will normally germinate satisfactorily. Deeper sowing will result in poor emergence, especially in tight soils.
Early in the season sow seeds deeper than 4 cm if necessary, as temperatures are higher and the seedbed will dry out more rapidly and possible deeper.
Fertilizer Requirements: Soil fertility is one of the key manageable factor among all the crop production factors in rapeseed production. Nutrient balance is extremely important for getting higher yields of rapeseed.
Nitrogen Utilization by Rapeseed: Once nitrogen is taken up by the plant roots, it moves freely within the plants where it becomes a constituent of protein and other cellular compounds such as chlorophyll. Rapeseed responds strongly to nitrogen fertilizer on deficient soils. Results of field experiments have shown that satisfactory and profitable yields of rapeseed can be produced on stubble land or in a Continuous cropping system with adequate fertilizer nitrogen and effective weed control. Under dry land conditions, profitable yield increases have been obtained in stubble field experiments, under good moisture, with rates of nitrogen upto 135 kg ha-1. Crop responses to fertilizer nitrogen are influenced by soil type, moisture conditions and nutrient balance. High rates should only be applied when a soil test indicates they are needed. Nitrogen applied to a summer fallow field with higher available nitrogen content is not justified and may cause delayed maturity, the response generally does not justify the expense.
Phosphorus Use by Rapeseed: The phosphorus requirements for good yields of rapeseed are equal to or greater than those for wheat or barley. Rapeseed takes up phosphorus from the soil rapidly in the early growth stages and continues to remove phosphorus over a period of more then eight weeks. Due to the immobility of phosphorus in soil, it is important that phosphorus fertilizer be placed close to the seed where the young plant has access to this nutrient early in the season.
An adequate supply of phosphorus enables the plant to develop a strong, healthy rooting system early in the season. This allows the plant to obtain nutrients and moisture from lower depths in the soils and survive periods of drought that may occur later in the growing season. Phosphorus helps rapeseed plants use moisture more efficiently. Adequate phosphorus also results in more uniform blooming, good seed production and faster maturity. Lack of available phosphorus results in a poorly developed root system, reduced branching of plants, and reduced yield. A severe phosphorus deficiency generally results in reduced growth and may show up as a dark green or purplish coloration of the leaves.
Potassium Utilization by Rapeseed: Rapeseed takes up nearly as much potassium as it does nitrogen and therefore, has a high potassium requirement. Potassium increases plant vigor, increases straw strength potassium helps speed healing of wound from insects or hail and wind.When a soil is deficient in potassium, the crop yield will be reduced, and responses to nitrogen and phosphorus will be small. In severe cases of potassium deficiency, the edges of older leaves will become yellow or scorched.
Weed Control: Rapeseed seedlings are very susceptible to weed competition in the first few weeks after emergence. An effective weed control during this period is vital. The crop canopy usually closes 6 to 8 weeks after emergence and then rapeseed becomes an excellent weed competitor due to increased canopy.
Irrigation Requirements: Number of irrigation varies with environmental conditions Temperature, rainfall), soil type, and variety/hybrid. Generally rapeseed requires 3-4 irrigations depending upon rains. Moisture stress during flowering, pod formation and seed development stages affects the yield.
Critical stages of irrigation:
– 4-6 weeks after emergence.
– Flower initiation.
– Seed formation stage.
INSECTS PESTS OF RAPESEED
Rapeseed crops is attacked by a number of pests, the most significant being red-legged earth mites and blue oat mites during establishment; and cabbage aphids, turnip aphids during flowering and pod formation.
Red-legged earth mite (Halotydeus destructor) Blue oat mite (Penthaleus major): The mites may seriously damage the crop establishment. They feed the foliage of seedlings and young plants, piercing the outer cells and sucking cell sap. Damaged leaves appear mottled and white or silver and heavily infested leaves may wilt or shrivel. Severely damaged plants usually remain stunted. Heavily infested seedlings and young plants may are damaged severely or killed.
Adult red-legged earth mites are somewhat flattened and about 1 mm long with velvety black bodies and bright red legs. They feed gregariously, usually on the upper side of the leaves.
Adult blue oat mites are about 1 mm long with pear shaped rounded, purple-blue, greenish blue or black bodies and bright pinkish red legs. Blue oat mites feed either singly or in small groups of five to ten mostly on the underside of the leaves.
Cabbage aphid (Brevicoryne brassicae) Turnip aphid (Linaphis erysimi)
Cabbage aphids and turnip aphids may infest rapeseed crops at any stage of growth but damage is most common during the flowering and pod formation period. The cabbage aphid is gray while the turnip aphid is green. Otherwise the two aphids are similar in size, general appearance and often occur in mixed infestations. Dense clusters of the sap-sucking aphids may form on the flowers and upper stems through the combined effect of their feeding, can seriously reduce or prevent pod set and podfill. The crop should be monitored regularly, particularly during flowering, to observe aphids population. If the population increases the economic threshold then spraying of suitable insecticide is recommended. Control of few aphids through chemical control not only uneconomical but may also result in destruction of the beneficial pests and predators, which often keep aphid, numbers down.
MAIN DISEASES OF RAPESEED
Sclerotinia Stem and Root Rot (Sclerotinia sclerotioram)
Symptoms: All parts of the plants i.e., stem, root, pod and leaves are attacked. Infected areas show cottony mycelium growth associated with large, round to irregular shaped, black sclerotia (2-15 mm in size). Sclerotia also develop within the pith. At maturity, the diseased tissue tends to shred upon handling. Releasing sclerotia into the soil or in the crop as it is harvested. Occasionally sclerotia are found in pods, side branches. Pods may also be infected and killed.
– Deep ploughing of soil will help to minimize the disease because burial of sclerotia at 8 cm checks the formation of apothecia and ascospores.
– A long rotation with at least four years between susceptible crops to reduce the incidence and severity of disease.
– Susceptible weed and volunteer plants should be destroyed to reduce the disease problem.
– Routine cleaning of seed followed: spiral cleaner removes nearly all sclerotia. This, too, will reduce the inoculum in the field.
– Seed treatment (for control of seed contamination by sclerotia of the pathogen), apply Thiabendazole at the rate of 400 mg/100 kg seed.
Stem, Leaf and Pod Spots, (Alternaria black spots)
Symptoms: The disease first appear on the cotyledons with light brown spots which rapidly turn black due to appearance of spore masses and act as source of infection for other healthy plant. Leaf spots range from gray to black depending upon moisture conditions. Each leaf lesion may be surrounded by chlorotic area. Lesions consisting of well marked concentric zones are often seen. Defoliation is an important consequence of leaf infection. Stem and pods spots are brown to black and may become large frequently developing grayish centre.
– Early varieties of rape may reduce loss due to Alternaria black spot.
– Weed control appears to be more critical for this disease.
– Use quality seed to reduce the inoculum of the pathogen.
– Seed treatment with fungicides is beneficial to control seed borne diseases.
– Resistant varieties provide the most economical way to control the disease.
– Foliar sprays with systemic fungicide control the disease to some extent but is unpractical for large acreage.
Harvesting is a critical operation, its harvesting at optimum time is very important because early harvesting can reduce seed quality and late harvesting can enhance pod shattering. Harvesting of Rapeseed-mustard is recommended when all the seeds are black and seed moisture is less then 15% (when 60-70% pods turn yellow). Crop should be harvested early in the morning. When the plants are moist, otherwise yield losses occur due to shattering.
THRESHING: When the harvested crop dry completely, It should be threshed in clear weather. Threshing can be done by thresher, bullocks or tractor after which winnowing is needed to clean the seed.
STORAGE: Damp or green seed, are impurities in the seeds can be a problem especially when weather conditions at harvest are unpredictable. Ventilation of seed in a store is essential in order prevent heating. It is recommended that seed should be dried properly at 9% moisture content, otherwise it will be damaged by fungi and insects and germination ability will be impaired.
Canola type: Dunkeld, Rainbow, Oscar, Con-I(early maturing, in 160 days), 19-H.
Non-Canola: BARD-1, Chakwal Raya, Sultan Raya, KS-75
Hybirds (imported): Hyola-420, Hyola 308, Hyola 401.
Local Hybrids: Tarnab-I, Tarnab-II, Tarnab-III
AVAIILABRATY OF SEED
Seed of these varieties can be purchased from the
– Oilseed Research Programme, National Agricultural Research Centre (NARC), Islamabad-45500
– Agricultural Research Institute, Tarnab, Peshawar,
– Regional offices of Pakistan Oilseed Development Board (PODB)
– ICI, Pakistan seeds (pvt.) Ltd. Lahore (for purchase of hybrid seed).