Hayes and Garber - Cucurbit Breeding

72 BREEDING CROP PLANTS
method (1), while method (2) gave seeds in 24 out of 47 spikes.
On these 24 spikes 50 per cent, of florets produced seeds.
Crossing Large -flowered Legumes. Oliver (1910) of the
United States Department of Agriculture, has made excellent
contributions to the technic of crossing. He emphasizes the
fact that in a cross between self-fertilized varieties, only a few
seeds are needed in FI. The large-flowered legumes, such as
Lathyrus, Phaseolus, Pisum, Stizolobium, and Vigna, should be
emasculated in the bud stage. The following account of crossing
Vigna, the cowpea, is taken from Oliver.
"In the evening it is found that the buds which will expand the next
morning are quite large and easily manipulated in emasculating (A).
FIG. 15. Flowers and young pods of the cowpea (twice natural size). (Copied
from photograph by Oliver.)
A. Flower bud showing condition on the evening of the day previous to opening of flower;
B, flower in the bud stage showing how the floral envelope is opened to gain access to
stamens for emasculation; C, flower with stamens removed showing the large stigma to
the left; D. emasculated flower the next morning after pollination; E, the young pod the
second morning after pollination; F, the same pod forty-eight hours after the pollination of
the flower. (After Oliver.)