186 INTRODUCTION TO BOTANY 



not thoroughly carried out, much .self-pollination and self- 

 fertilization is sure to occur. Corn which is self -fertilized 

 produces smaller and less -vigorous plants the next season 

 than cross-fertilized corn (fig. 159). Detasseling has there- 

 fore been found to increase the yield of corn more than ten 

 bushels per acre. 1 



175. Williams's method. The method of corn breeding as 

 above outlined has been criticized on the ground that little or 

 no attention is paid to the productiveness of the plant used 

 as the source of pollen. A new system devised by Professor 

 C. G. Williams, of the Ohio Agricultural Experiment Station, 

 provides for equally careful selection of the staminate and 

 pistillate parents. The system in its barest outlines, as stated 

 by Professor Williams, provides for 



1. The usual ear-row test. Only a portion (usually about one half) 

 of each ear is planted. The remnant is carefully saved, and when the 

 ear-row test has shown which ears are superior, recourse is had to the 

 remnants to perpetuate these ears in a later season. 



2. An isolated breeding plot in which are planted the four or five 

 best ears as demonstrated by 1. Not the progeny of the best ears, but 

 the original ears. Usually the best ear is used for staminate plants and 

 planted on each alternate row in the small breeding plot. All the plants 

 from the other ears going into the plot are detasseled. 



The pedigreed strains produced in the breeding plot are multiplied 

 for general field use and also furnish ears of varying worth for a second 

 ear-row test, if it is desired to continue the improvement. 



The ear-row test need not be isolated, for no seed is taken from it. 

 Neither is there any need for detasseling until the breeding plot is 

 reached. 



176. Hybridizing. As has already been shown (sects. 13 

 and 127), seed production is the result of fertilization of the 

 egg within an ovule by a pollen grain. Usually the pollen 

 and the ovule concerned in fertilization are derived from 

 plants of the same species. Often pollen of another species is 



1 For details about corn breeding see De Vries, Plant Breeding, The Open 

 Court Publishing Company, Chicago ; Bulletin 100, Illinois Agricultural Ex- 

 periment Station ; and Circular 66, Ohio Agricultural Experiment Station. 



