Hayes and Garber - Cucurbit Breeding

CHAPTER XI
COWPEAS, SOYBEANS, AND VELVET BEANS
Cowpeas, soybeans, and velvet beans belong to the group
of naturally self-fertilized crops. The fundamental principles
involved in breeding crops of this group have already been discussed.
It suffices here to point out that the method of breeding
these three legumes does not differ essentially from that for the
group.
COWPEAS (Vigna sinensis)
Origin. A wild plant closely related to the cultivated cowpea
grows quite generally over the continent of Africa. The wild
form differs from the cultivated in having smaller seeds and in
having pod valves which coil in ripening. The two forms may
be hybridized with ease. This fact and the fact that wild cowpeas
have been found in no other place, are generally accepted as
evidence (Piper, 1916) that the cultivated form arose in Africa.
Description and Inheritance. The cowpea resembles the
garden bean in general appearance. Some varieties grow erect
while others are vine-like and trail over the ground. The pods
are rather long and contain from 6 to 15 seeds each. Flowers
are white or nearly white and pale to medium violet purple and
are shaped like those of the garden pea.
Seed coats vary a great
deal in color some are mottled, others uni-colored. The life
period of this plant is too long to permit its growth very far
north, and for this reason an earlier maturing cowpea is desirable.
Size and shape of pod and seed have been used to separate the
larger groups. No studies of inheritance of these major differential
characters have been made.
Color inheritance with particular reference to the seed-coat
has been studied by Spillman (1911) and more recently by
Harland (1919a, 6, c, 1920). Anthocyanin coloration in the stem
and leaf stalk is dependent on a single factor difference X,
dominant to its absence. The inheritance of seed coat pattern
involves factors B (black), N (buff),
143
M (Maroon) and R (Red),