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 stigrr.a 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.) 



