The Seed in Plant Production 



395 



From these results it seems just to conclude that, in gen- 

 eral, a more vigorous growth, and consequently a better stand 

 in the field, is secured by employing only the heavier seed. 



235. Experiments with wheat. The effect of size of 

 seed on production has been with no other plant so exten- 

 sively studied as with wheat. The evidence is most con- 

 tradictory. The majority of the results seem to favor 

 the view that large or heavy seed are preferable, especially 

 when among the small seed are included distinctly imma- 

 ture grains. With wheat the factors are complex, for 

 size may be considerably affected by plumpness, and the 

 latter may be due largely to starch and water content. 

 Additional starch in the grain may not affect the vigor 

 and yield of the plant secured from such seed. Again, 

 in the same variety, there may be different types or strains, 

 some with larger grains, some with smaller, although 

 the yields may run practically the same. All these factors 

 may affect the experiments. The results of grading and 

 testing seed wheat are shown in subsequent tables. 



In the first case reported by Zavitz, the seed were 

 selected from both winter and spring wheats, and the 

 experiments were continued five and eight years, respec- 

 tively, but each crop was grown from previously unse- 

 lected seed : 



