IMPROVEMENT OF WHEAT 39 



While there may be a few slight or questionable exceptions 

 to the general rule/ it can be said that enough results of 

 scientifically conducted experiments are now at hand to prove 

 conclusively that by means of selection alone the yield of wheat 

 can be materially increased, even in a few years. The gain 

 from the increased yield is much greater than the cost of mak- 

 ing the selection, if the work is carried on systematically 

 through a series of years. 



A method frequently used is the selection of plump kernels 

 from grain in the bulk. While there is doubtless some ad- 

 vantage in this method, it cannot give the best results, for 

 many of the plump kernels may come from imperfectly filled 

 heads, or from plants having few or weak suckers. Selection 

 is a choosing of the individual, which, in the case of wheat, is 

 a stool with several spikes and many seeds. When mutually 

 antagonistic characters are desirable, such as earliness and 

 productiveness, selection is very difficult and requires good 

 judgment. By proper selection, not only may yield be in- 

 creased, but all the other variations above mentioned may be 

 influenced. Prolificacy of races may be fixed. Another im- 

 portant quality to be considered is vigor. Indeed, it has been 

 held that the vigor and productiveness of the parent are far 

 more important than its mere size. 



The chance of improvement by selection increases as the 

 number from which individuals may be chosen grows larger. 

 The plant breeder has a great economic advantage over the 

 animal breeder, for the expense of producing seeds for individ- 

 ual plants is so small that only a few of the best seeds are 

 kept, while in animal breeding expense ordinarily forbids disre- 

 garding more than a small per cent as poor specimens. Pro- 

 digious variations may be induced by a long continuation of the 

 selective process. Rigid selection systematically and scientifi- 

 cally practiced on a large scale by European seed growers in 

 the last century has increased the sugar content of sugar beets 

 more than 100 per cent. 2 Six years of selection at the Minne- 

 sota station increased the length of flax fiber over 20 per cent. 

 Hays estimates that the farmers have increased the yield of 

 corn 20 per cent by annually selecting the largest and best 

 formed ears from among many thousands. The process has 



1 Thorpe, Harper's Mag., 15:302. 



2 Yearbook U. S. Dept. Agr., 1901, pp. 217-218. 



