148 



BREEDING CROP PLANTS 



Parents :. ... (Y)hh? 



Cotyledons yellow 



Seed-coats yellow 



F, 



Cotyledons 



Seed-coats 



F 2 (Y)HH 



25 per 

 cent. 



Cotyledons. yellow 



Seed-coats green 



The inheritance of color of pubescence of soybeans is simple. 

 The factor for tawny color is allelomorphic and dominant to the 

 factor for gray Segregation for color of seed and color of 

 flower occurred in natural hybrids noted by Piper and Morse 

 (1910). The number of plants observed was not sufficiently 

 large to determine the factors involved. 



Breeding. Pure-line selections of soybeans have been made 

 on the basis of oil content, yield (both of seed and forage), 

 persistence of leaves, and other economic characters. Varieties 

 like Wisconsin Black retain their leaves green until practically 

 all the pods are ripe. Another character of considerable impor- 

 tance in the soybean is frost resistance. It has been found in 

 trials at the Arlington Experimental Farm near Washington, 

 D.C., that varieties differ appreciably in this character in both 

 early spring and late fall. Most of the late varieties were killed. 

 This would indicate that the hereditary difference between 

 varieties in frost resistance is without doubt in part a matter of 

 the degree of maturity which the plants have reached at the 

 time of frost. Considerable artificial hybridizing has been done 

 by Morse of the United States Department of Agriculture. 

 While soybeans have been grown in the orient since ancient 

 times, their general growth in the United States and Europe is 

 comparatively recent. As a consequence investigation with 

 this crop has not proceeded much beyond the stage of variety 

 testing and strain isolation. Then, too, there are so many 

 varieties of different habits of growth, that it has been possible 

 to find a variety adapted to almost any locality. As the real 

 value of the soybean becomes more generally appreciated, it will 

 undoubtedly receive more attention from the breeding stand- 

 point. 



