144 BREEDING CROP PLANTS 



Factor system for seed coat colors: 



Black B N M R 



Black B N m R 



Black B n m R 



Black B n M R 



Brown b N M R 



Buff b N m R 



Maroon b n M R 



Red 6 n m R 



New-Era pattern E R 



White Absence of R 



Purple color of the ripe pod is dependent on one main factor 

 difference P. Each of the three factors B, E, and P, produces 

 anthocyanin pigmentation in the young pod, calyx, and peduncle. 

 Whether these three factors, each dominant to its absence, con- 

 stitute a triple series of multiple allelomorphs or occupy different 

 loci very near together in the same chromosome, has not yet 

 been established. 



In crosses between black cowpeas and the variety Black Eye, 

 Spillman found the patterns known as Holstein (pigmented area 

 covering micropylar end and isolated spots of pigment on the non- 

 pigmented area) and Watson Eye (pigmented area around hilum 

 with indistinct margin at micropylar end of seed ; micropylar end 

 covered with fine dots of pigment) appearing in the F z generation. 

 This indicated the origin of varieties which bear these seed-coat 

 patterns. 



The inheritance of flower color in the cowpea, according 

 to Harland, is rather simple. In crosses between dark and pale, 

 also between dark and white, the segregation in the F 2 generation 

 proved to be that of a monohybrid with dark behaving as the 

 dominant. Spillman (1913) found correlations between the 

 production of certain seed-coat colors and the occurrence of 

 anthocyan in the flowers. 



Root-knot (Heterodera radicicola) and wilt (Neocosmospora 

 vasinfecta, var. tracheiphila) are the two most serious diseases of 

 cowpeas. The former is due to the attack of a nematode whereas 

 the latter is due to a fungus. The variety known as the Iron cow- 

 pea possesses resistance to both of these diseases. According to 

 Orton (1911) this disease resistance is inherited as a dominant 

 character. The F 2 generation is too variable to be satisfactorily 

 explained on a monohybrid basis, However, it behaves in a 



