ntroduction
Cowpea(Vigna sesquipedalis)also known as southern pea and black eye pea,is one of the most important vegetables.It is cultivated for its long,green or purplish pods to be cooked as vegetable or for dry seeds used as pulse.Cultivated cowpea belongs to 3 groups-common cowpea,producing 20-30cm long pods withs small seeds.Catjang bean producing 7-13cm long pods with 5-6mm kidney shaped seeds and asparagus beanor yard long been producing 30-90cm long.In india,cowpea has been known since the vedic period and it is grown almost throughout the country.
Climatic Condition
Cowpea can be grown almost in any type of soil but well drained loam or slightly heavy soils are better.Saline or alkaline soils are not good.It is awarm season crop and can be grown in all tropical and subtropical areas.It can tolerate drought to some extent but cannot tolerate waterlogging. The germination is better at 12-15 degree centigrade temperature and the crop thrives between 21-35 degree Celsius temperature.Frost is harmful to this crop.Partial shade can be tolerated.
Land preparation
Prepare the land by ploughing at right moisture situation and level the surface by planking to conserve the moisture. Open the planting lines at required spacing using a country plough.
Seeds & Sowing
Local Cowpea selection having higher yield potential is more economical. High yielding small seeded introduced varieties like V- 118, Pusa Sampada can also be grown.Line sowing with a spacing of 30 x 10 cm for small seeded and 45 x 15 cm for bold seeded is more ideal. It is better to sow in plough-sole so as to place the seed in the moist zone at a depth of 5 cm. Ensure an optimal plant population for better yield potential.
Time of sowing
In most of the areas,cowpea is grown during the rainy and summer seasons.Sowing in june-july is common for rainy season crop,but it could be extended to august for early maturing bush varieties.Similarly sowing in February-march is common for summer crop,particularly in northern plains,which could be extended upto mid-april. A seed rate of 12-15 kg/ha is enough for rainy season crop,while 20-25kg/ha is required during summer.Keep a spacing of 45-60 cm from row to row during rainy season and 30 cm during summer season.The plant to plant distance may be kept 10-15 cm.
Inter—cultivation
Use of Rotary hoe in the line planted crop helps in minimization of weeds. Early weed control for first 45 days is crucial to ensure higher yield.
Manures and Fertilizers
Depending upon availability,15-20 tonnes/ha of farmyard manure may be incorporated in the soil at the time of field preparation.Being a nodule forming crop,cowpea does not require heavy nitrogen fertilization.Thus only 20-25kg/ha N along with 50-70kg/ha of P205 and K2O may be applied as basal dose before sowing. Seed inoculation with Rhizobium culture is beneficial.In zinc deficient areas zinc sulphate @ 10-15kg/ha may be applied in the soil.
Irrigation
Cowpea requires lighter but frequent irrigations.It is sensitive to waterlogging.During rainy season no irrigation may be required but in absence of timely rains supplemental irrigations may be needed.The summer crops needs irrigation after every 8-12 days depending on soil and wether conditions.In sandy loam soil irrigation at 75% available moisture is optimum.
Aftercare
Effective management in first 25-30 days of the crop period is essential.At last 2 weedings and hoeing are needed to check the weeds.Fluchloralin@ 1kg/ha are preplant incorporation in the field or alachlor/nitrofen @ 2.0kg/ha each as pre emergence spray are effective in controlling the weeds. The bush type cowpea can also be intercropped with maize.Cowpea is suitable to fit in several cropping sequences consisting of cereals and vegetables.Spraying of maleic hydrazide(50-200ppm)before flowering improves pod set and yield.
Harvesting
Harvesting: The pods are harvested when adequately developed and remain tender.Picking of pods 15 days after pod setting is ideal for vegetable purpose compared with other picking stages.The harvesting starts from 45-50 days in the early cultivars which may continue up to 100 days in flushes.Depending on the season and variety,grain crop matures in 75-125 days.If on a smaller scale,the mature pods are picked up at intervals.On an average cowpea provides 50-80q/ha of green pods,the dry seed yield being 12-15q/ha.For seed purpose,the harvested pods are dried for a few days before threshing.The threshed seeds are also dried sufficiently before storage in a cool and dry place.