Hayes and Garber - Cucurbit Breeding

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 b n m R
E R
New-Era pattern
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, constitute
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 nonpigmented
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 2 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 Fz 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 cowpea
possesses resistance to both of these diseases. According to
Orton (1911) this disease resistance is inherited as a dominant
character. The F% generation is too variable to be satisfactorily
explained on a monohybrid basis. However, it behaves in a