EXPERIMENTS IN FIELD PLOT TECHNIC 37 



In the wheat variety test of 1920 the average yield of border rows 

 differed from the average yield of interior rows by 12.30 per cent and 

 the mean coefficient of competition was 19.79 per cent. These figures 

 represent the average determinations when the two varieties of rye 

 and the border yields of the varieties of wheat adjoining them were 

 eliminated. The correlation between competition and relative yield, 

 date of heading, and date of maturity were determined for this test 

 and the coefficients of correlation are shown in Table 13. 



TABLE 13. CORRELATION OF COMPETITION WITH VARIOUS CHARACTERISTICS IN 

 WHEAT VARIETY TEST 1920. 



Character Mean difference be- Coefficient of correlation 



tween competing with competition 



varieties 



Date of heading 2.3 days .515 .048 



Date of maturity 2.7 days .552 .045 



Yield 28.9% +.582 .043 



Competition in this test was negatively correlated with earliness of 

 heading and maturity and positively with yield. All of the correla- 

 tion coefficients are clearly significant. In other words, there was a 

 rather pronounced tendency for the early and high-yielding varieties 

 to profit in competition. To a considerable extent the early varieties 

 were the high yielding varieties in this test, as indicated by the fact 

 that the correlation coefficient for date of heading and yield was .511 

 .051, and that for date of maturity and yield was .642 .041. Al- 

 though it is clear from these results that early, high-yielding varieties 

 excelled in competition, it is not clear whether they did so chiefly as a 

 result of their earliness or chiefly as a result of their yield. 



TABLE 14. CORRELATION OF COMPETITION WITH VARIOUS CHARACTERISTICS IN 

 WHEAT VARIETY TEST 1921. 



Character Mean difference be- Coefficient of correlation 



tween competing with competition 



varieties 





Similar results were obtained in the wheat variety test of 1921 

 in which the difference between the average yield of border and in- 

 terior rows was 12.89 per cent and the mean coefficient of competition 



