EXPERIMENTS IN FIELD PLOT TECIINIC 



27 



tition serves to illustrate the phenomenen, although the competition 

 between wheat and rye has little significance in itself as regards va- 

 riety tests in general, since wheat and rye are not commonly included 

 in the same test. 



Ordinarily the competition between varieties of the same crop 

 is not so extreme. There are, however, a number of cases in which 

 a variety of wheat or oats profited almost as extremely in competition 

 with other varieties of the same crop as did the rye in competition 

 with wheat in the cases cited above. The wheat variety, Michigan 

 Wonder No. 116, which grew between two other wheat varieties, 

 Leap's Prolific and Poole Selection, in 1921, gave the following results, 

 as an average of the four series: 



The effect of competition in this case is almost as pronounced 

 as in the case of the rye, although the three wheat varieties concerned, 

 when protected from competition, gave almost equal yields and differed 

 little in date of heading, date of maturity, and height. In this case 

 a small difference in actual value between the varieties, as indicated 

 by their yields when protected from competition, is greatly increased 

 when their yields in adjacent single rows are compared. 



A striking case of competition in the oats variety test of 1921 was 

 that of the three varieties Sterilis Selection, Fulghum, and Kherson, 

 the check variety. Their average yields were as follows: 





