IMPROVExMENT OF MAIZE 



187 



the male and dent maize the female parent, McCluer^ has 

 shown both sweet and dent grain in the current cross, and that 

 the dent grain when grown would show sweet characters. There 

 is a strong tendency for color, where it is a character of the 

 endosperm, to show in the current cross. 



Webber has shown that the aleurone layer may be affected 

 by the current cross. Cuzco, a soft variety, with heliotrope- 

 purple color in the aleurone layer, was crossed upon several 

 varieties of dent maize, and grain resulting from such fertilization 

 contained the same or similar color in the aleurone layer.^ The 

 immediate effect of pollen upon the color when the color is in 

 the seed coat, as in calico maize, is denied by some, and the 

 observed instances have been explained by assuming that the 

 seed of the female parent was impure. 



253. Degree of Close Breeding. — There may be several degrees 

 of closeness in breeding maize : (i) Between pollen and ovules of 

 the same plant; (2) between pollen and ovules of plants grown 

 from seed from the same ear ; (3) between pollen and ovules 

 of plants grown from seed from different plants of the same 

 variety. The closeness of relationship of the plants furnishing 

 the seed may vary between very wide limits. They may have 

 had a common ancestor but one generation back, or they may 

 have been unrelated in one or both ancestors for many genera- 

 tions ; (4) between pollen and ovules of plants grown from seed 

 of different varieties ; (5) between pollen and ovules of plants 

 grown from seed of different types. 



254. Close Breeding. — Since cross-fertilization appears to be 

 the rule in maize, it is generally considered desirable to avoid 

 any practice which would induce close-fertilization. (106) Hop- 

 kins states that he has secured data pointing toward an injurious 

 effect of close-pollination and recommends cross-pollination in 



1 111. Bui. 21, p. 87. 



2 Xenia, or the immediate effect of pollen in maize. U. S. Dept of Agr., Div. 

 Veg. Phys. and Path. (1900) BuL 22. 



