WHEAT 



139 



paragraph on the improvement of corn. More careful 

 experimenters will desire to measure off accurately a 

 fraction of an acre for each variety. The test is most 

 valuable when it has been carried on for several years on 

 the same farm, since 

 the influence of sea- 

 sonal conditions may 

 be more accurately de- 

 termined. 



127. The head-row 

 test. — When the best 

 variety has been se- 

 lected, still further 

 opportunity for im- 

 provement is to be 

 found in the selection 

 of the highest yield- 

 ing plants in this va- 

 riety. Individual 

 plants like ears of 

 corn vary markedly in 

 their ability to yield. 

 If, therefore, the high- 

 yielding plants can be 

 found and used for per- 

 petuation, great oppor- 

 tunities for increasing 

 the yield are possible. 

 The method of making this selection is known as the head- 

 row test. This test consists in going into the field at 

 harvest time and selecting under normal conditions of 

 growth a number of the most promising individuals. 

 From 25 to 1000 heads, representing as many plants, may 



Fig. 47. — Head-row test at the Ohio Sta- 

 tion showing variation in erectness of heads. 



