Introduction
Cowpea (Vigna unguiculata subsp unguiculata and subsp sesquipedalis) also known as the yard-long bean is one of the most important legume vegetables. It is cultivated for its tender green long pods and also for seeds. It is a twining annual herbaceous plant. The stem is slightly ridged and glabrous. The leaves are trifoliate and alternate. Pods are long and cylindrical. Its foliage is also used as fodder or green manure. Cultivated cowpea belongs to 3 groups: common cowpea (producing 20 to 30 cm long pods with small seeds), catjang bean (producing 7 to . 13 cm long pods with 5 to 6 cm kidney-shaped seeds), and asparagus bean or yardlong bean (producing 30 to 90 cm long fleshy pods with elongated kidney-shaped, 8 to 12 mm long seeds). In India, cowpea has been known since the Vedic period, and it is grown almost throughout the country. In Kerala, Odisha, and West Bengal, it is grown as a floor crop in coconut gardens and as an intercrop in tapioca. It can be grown as a pure crop in rice fallows during rabi and summer, and also in homestead gardens throughout the year.
Table of Contents (toc)
Climate and soil
It is a warm-season crop and can be grown in all tropical and sub-tropical areas. It can tolerate drought to some extent but cannot tolerate water-logging. The germination is better between 12-15°C temperature and the crop thrives best between 21-35°C temperature. Frost is harmful to this crop. Partial shade can be tolerated. The varieties showed varying responses to temperature and day length. 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.
Varieties
The criteria in the development of cowpea varieties for vegetable purposes have been primarily the pod yield and its quality. However, some varieties are dual purpose and are suitable for green pods as well as dry seed production.
Arka Garima: Plants are tall, vigorous, bushy, spreading with light green leaves and purple flowers. Pods light green, long, thick, round, fleshy, and stringless, tolerant to heat and drought. Yield potential of 17-19 tonnes/ha in 90 days of crop duration. Recommended for Madhya Pradesh, Maharashtra, Karnataka, and Kerala.
Arka Mangala: A pole-type vegetable pod variety, developed through pure line selection. Pods ready for picking in 60 days, 75-80 cm long, green, round, stringless with a crisp texture. Yield 20 tonnes/ha in 100 days. Suitable for Kharif and rabi seasons.
Arka Samrudhi: Plants erect, bushy, photo insensitive, early with pods above the canopy. Pods green, medium-thick, medium-long round, tender, fleshy without parchment. Good cooking qualities. Duration 70-75 days. Pod yield 19 tonnes/ha.
Arka Suman: Plants are a bushy, photo-insensitive, erect, early variety (42 days for first picking). Pods medium long (17-20 cm), medium-thick, smooth, light green, fleshy, crisp with good cooking quality, and pods are borne above the canopy. Yield potential of 19.0 tonnes/ha in 80 days.
Bidhan Barbati 1: Plants compact, determinate with dark green foliage. Yield is 13.4 tonnes/ha, resistant to cowpea mosaic and cowpea golden mosaic virus.
Bidhan Barbati 2: Plants semi-determinate, yield 15.9 tonnes/ha, very low incidence of cowpea mosaic and cowpea golden mosaic virus.
Kashi Gauri: A bush type, dwarf, photo-insensitive, and early variety suitable for growing in both spring-summer and rainy seasons. Flowering starts in 35-38 days and pods get ready for harvest in 45-48 days after sowing. Pods are about 25 cm long, light green, soft, fleshy, and free from parchment. Resistant to golden mosaic virus and Pseudocercospora cruenta, pod yield 100-120 q/ha. Released for cultivation in Punjab, Uttar Pradesh, and Jharkhand.
Kashi Kanchan: Dwarf and bush type (height 50-60 cm), photo-insensitive, early flowering (40-45 days after sowing), and early picking (50-55 days after sowing) suitable for growing in both spring-summer and rainy seasons. Pods about 30-35 cm long, dark green, soft, fleshy, and free from parchment. The green pod yield is 150-175 q/ha. Resistant to golden mosaic virus and Pseudocercospora cruenta. This is released for cultivation in Uttar Pradesh, Punjab, Bihar, Chhattisgarh, Odisha, Telengana, Andhra Pradesh, and Madhya Pradesh.
Kashi Unnati: Plants dwarf and bushy, height 40 50 cm, branches 4-5 per plant, early flowering (30-35 days after sowing), first harvesting at 40-45 days after sowing, produces 40-45 pods per plant. Pods 30-35 cm long, light green, soft, fleshy, and free from parchment. Resistant to golden mosaic virus and Pseudocercospora cruenta, and gives green pod yield of about 125-150 q/ ha. Released for cultivation in Punjab, Uttar Pradesh, and Jharkhand.
Lola: Plants trailing type, smooth and extra-long pods, glossy light green colored long pods with purple tip, black seeds. The average length of the pod is 53 cm, the average pod weight is 22 g, the number of pods/plant is 20-22, and productivity is 20 tonnes/ha.
Narendra Lobia 1: Plants are long 40-45 cm with large green leaves. Green pods (28-30 cm long) with the purple terminal end. The pod containing 10-12 seeds is bold with seed and black hilum. It takes 45-48 days to give the first pod harvest and 75-80 days for seed maturity. Being photo-insensitive, suitable both for rainy as well as summer seasons.
Philippines Early: Plants have trailing growth habits. The first green pod harvest is available after 55-60 days of sowing. The pods are about 29 cm long, creamy-white, fibreless, containing about 17 seeds/pod. More popular in Madhya Pradesh.
Pusa Barsati: Suited for rainy season cultivation. Early-maturing giving first picking in 45 days. Pods light green, 25 to 28 cm long, containing large green seeds.
Pusa Dofasli: Plants are dwarf, bushy, light green, erect, about 18 cm long with creamy-white seeds having red-colored hilum; yielding the first harvest in 50 days. Photo-insensitive can be grown in rainy as well as summer seasons.
Pusa Komal: Plants are dwarf and bushy and the first green pods are available in about 60 days. Pods light green, cylindrical, 20-22 cm long with creamy-white seeds. Resistant to bacterial blight and suitable for rainy as well as spring-summer sowing.
Pusa Phalguni: Plants dwarf and bushy, yielding first picking in 60 days. Pods dark green, erect, about 12.5 cm long with cylindrical white seeds. More suited for spring sowing.
Pusa Rituraj: Plants bushy and prolific-bearer, 22 24 cm long, thin, with brown seeds when dry. Highly photo-thermo insensitive can be grown during the rainy season as well as summer. Takes 40-45 days to yield the first harvest. Dual-purpose variety since its pods as well as seeds is suitable for cooling.
Pusa Sukomal: Plants semi-dwarf, erect; pods light green, round, meaty, less fibrous, around 30 cm long, and 1 cm thick. Maturity in 42-45 days during Kharif and 55-60 days during summer. Highly resistant to golden. yellow mosaic virus and leaf spot disease.
Selection 263: Plants are dwarf, can be grown in both spring and rainy seasons. Pods are green thick, fleshy, tender, and medium-long (20 cm), flat and tender. First harvest in 45-50 days. Suitable for the rainy season as well as summer. Less susceptible to mosaic virus and yields much better than Pusa Dofasali in both seasons. Developed at PAU, Ludhiana.
Vyjayanthi: Plants trailing type, long, light red colored pods, brown seeds, the average length of pods 50.6 cm, average fruit weight 16 g, and productivity is 12.6 tonnes/ha.
Cultivation
Sowing
In most areas, cowpea is grown during the rainy and summer seasons. Sowing in June-July is common for rainy season crops, but it could be extended to August for early-maturing bush varieties. Similarly, sowing in February-March is common for the summer crops, particularly in northern plains, which could be extended up to mid-April. In areas having a mild climate, the crop is also cultivated during the winter season. In hills, it is sown during April-July.
A seed rate of 12-15 kg/ha is enough for a rainy season crop, while 20-25 kg/ha is required during summer. In mixed sowing with other crops, the seeds rates may be reduced to half. Keep a spacing of 45-60 cm from row to row during the rainy season and 30 cm during summer. The plant-to-plant distance may be kept 10-15 cm. Sowing may be done by seed drill. Adequate moisture in the soil is essential before sowing. For yard long beans, spacing of 150 cm between the rows and 30 cm between the seeds is recommended.
Manuring and fertilization
Depending upon availability, 25 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 20-25 kg/ ha N along with 50-70 kg/ha of P₂O, and K₂O may be applied as basal dose before sowing. The doses of P and K may be based on the soil test values to economize on fertilization. Seed inoculation with Rhizobium culture is beneficial. In zinc deficient areas, zinc sulphate @10-15 kg/ha may be applied in the soil.
Seed inoculation and pelleting
Cowpea seeds should be inoculated with Rhizobium and pelleted with lime for quality seed production. Around 250-375 g of Rhizobium is sufficient for seeds/ha lime pelleting in acid soils. Specific inoculant has to be used for the specific leguminous crop. Do not expose the Rhizobium culture to direct sunlight or heat.
Mix the inoculants uniformly with the seeds by using the minimum quantity of water (instead of water, either 2.5% starch solution or Ganji neeru or vellum of the previous day can be used in order to ensure better stickiness of the inoculant with the treated seed material). Take care to avoid any damage to the seed coat. Dry the inoculated seeds under shade over a clean paper or gunny bag and sow immediately. The Rhizobium culture or the inoculated seeds should not be mixed with chemical fertilizers.
Lime pelleting
• Add finely powdered (300 mesh) calcium carbonate to moist fresh Rhizobium treated seeds and mix for 1-3 minutes until each seed is uniformly pelleted. Depending on the seed size, the following quantity of lime will be required.
• Small seeds 1.0 kg/10 kg of seed Medium size seeds 0.6 kg/10 kg of seed
• Large size seeds 0.5 kg/10 kg of seed.
• Spread out the pelleted seeds on clean paper to harden. Sow them as soon as possible. However, lime pelleted seeds can be stored for up to one week in a cool place prior to sowing.
Land preparation
Prepare the land and bring the soil to a fine tilth. Make ridges and furrows at 150 cm spacing for yard long beans and 60 cm for bush cowpea. Apply full organic manure, half N, and a full dose of P and K as a basal dose. Irrigate through furrows lightly a day before sowing. Open narrow furrows on edge of the ridge and sow the seeds at every 30 cm for yard long beans and 10 cm for bush cowpea. Open shallow furrows of 3-4 cm depth. Sow. the seeds and cover with a mixture of fine FYM. After two days, irrigate lightly to allow germination. Top dress the crop with the remaining 50% of N after 25 days of germination.
Irrigation
Cowpea requires lighter but frequent irrigations. It is sensitive to waterlogging. During the rainy season, no irrigation may be required but in absence of timely rains, supplemental irrigations may be needed. Similarly, in early sowing in the pre-monsoon period, 1 or 2 irrigations may be essential. The summer crop needs irrigation after every 8-12 days depending on soil and weather conditions. In sandy loam soil irrigation at 75% available moisture is optimum.
Aftercare
Effective weed management in the first 25 30 days of the crop period is essential. At least two weedings are needed to check the weeds. Fluchloralin @ 1 kg/ha as pre-plant incorporation in the field or Alachlor or Nitrogen @2 kg/ha each as pre-emergence spray are effective in controlling the weeds.
The pole-type varieties need support since the plants have twining growth habits. Such varieties are often restricted to kitchen gardening. However, in eastern Uttar Pradesh, Odisha, Kerala, and Coastal. Karnataka they are also grown as a mixed crop. 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 (50-200 ppm) before flowering improves pod set and yield.
Harvesting and post-harvest management
The pods are harvested when adequately developed and remain tender. Picking of pods 15 days after pod setting is ideal for vegetable purposes compared with other picking stages. The pods at this stage are longer, less fibrous, with more protein content, and are more succulent. The harvesting starts from 45-50 days in the early cultivars which may continue up to 100 days in flushes. In all, 4-5 pickings are done in bush type and 6-8 pickings in pole type. Depending on the season and variety, the harvesting varies. Generally, for grain purposes, the pods are allowed to full maturity on plants and then the crop is harvested and threshed after proper drying. If on a smaller scale the mature pods are picked up at intervals. On average, cowpea provides 5-8 tonnes/ha of green pods, the dry seed yield being 1.2-1.5 tonnes/ha. For the remunerative price, it is better to remove the insect and disease-damaged pods before marketing. Similarly fibrous and over mature pods should also be sorted out. For seed purposes, 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.
