Breeding of Vegetable, Spice and Tuber crops (2+1)

Cowpea

• Cowpea (Vigna unguiculata) also called as southern pea and black eyed pea belongs to family leguminosae.
  
• Less attention has been given to the vegetable cowpea. It is a nutritious leguminous crop low in anti-nutritional factors.
  
• It has a wide range of ecological adaptations and can be grown more widely.
  
• In fact, it probably has the greatest potential among all food legumes in the semi-arid to sub-humid tropical areas.
  
• The typical vegetable cowpea is characterized by a long pod (>30 cm), stringless pods, fleshy pod pericarp, thin and long seeds and higher monosaccharide: polysaccharide ratio. Pole and bushy types are available in vegetable cowpea.

Origin

• Africa is considered as the primary centre of origin of 170 species of genus Vigna, 22 are found in India.
  
• The crop spread from Africa to Asia and Europe through Egypt. Now cowpea is widely distributed throughout the tropics and subtropics.

Floral biology

• The flower opens early in the morning, closes before noon and falls down on the same day.
• The extra floral nectarines at the base of the corolla attract ants, flies and bees but a heavy insect is required to depress the wing petal and expose the stamen and stigma.
• Cowpea flower bloom between 6.30 and 7.00 a.m.
  
• The process of opening of corolla takes 45-60 minutes.
  
• Anther matures and starts dehiscing about 78 hours before the time of opening corolla.
  
• Pollen remains viable for 42 hours at room temperature and relative humidity 91%. Stigma becomes receptive from 12 hours before blooming to 6 hours after blooming.

Breeding goals

• High green pod yield (vegetable type varieties)
• High seed yield (dry-seed type varieties)
• High fodder yield (fodder type varieties)
• Dual purpose (seed and vegetable type and seed and fodder type)
• Earliness
• Appropriate plant type (erect, determinate for vegetable and seed type cultivars and spreading for fodder type cultivars)
• Wider adaptability
• Photo-insensitive
• Short tender pods for whole pod processing
• Long tender and stringless pods for fresh consumption
• Varieties suitable for inter cropping
• Resistance to disease
• Resistance to insects
• Better seed quality

Cytogenetics

• It is true diploid with 2n=22. Sen and Bhowal (1960) made cytotaxonomic studies on Vigna sinensis (L.) Savi, V. catjang (Bur.M) Waqlp. and V. sesquipedalis (L.) Fruw, popularly known as cowpea, catjang bean and asparagus bean.
  
• The three cultivated species could be easily crossed among themselves. The hybrids among them were fertile like intervarietal hybrids.
  
• Chromosome number of each of three cultivated species was found 2n=22. As mentioned elsewhere, all the above cultivated species are put under Vigna unguiculata.