42 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN 49 



tion with competition in each case, though some of the coefficients 

 are insignificant. It is clear therefore that early varieties are, in gen- 

 eral, able to compete more strongly, but the extent of this relation is 

 quite variable. The grain-straw ratio showed no significant relation 

 to competition in any of the experiments of 1919, and was not deter- 

 mined for the succeeding tests. Height was correlated positively with 

 competition in the one test in which height was determined, the wheat 

 variety test of 1921. In this test height was more closely related to 

 competition than were date of heading, date of maturity, or yield. 



In the oats variety tests, the relation of early maturity to compe- 

 tion is particularly marked, the coefficients of correlation in both oats 

 variety tests being distinctly greater for date of maturity and compe- 

 tition than for yield and competition. In the wheat tests there was 

 little difference in the degree of relation to competition between earli- 

 ness and yield. In the one test of barley varieties conducted, yield 

 was more closely correlated with competition than was either the 

 date of heading or date of maturity, but none of the three showed a 

 clearly significant correlation. 



It is clear that in these trials the early, high-yielding varieties 

 profited by competition. To a considerable extent these may be the 

 same varieties, for the correlation of earliness and yield was high in 

 most of the tests conducted. The relation of earliness and other 

 characters to yield under Missouri conditions will be considered more 

 fully in another paper, but data of interest in this connection are ap- 

 propriate here. The coefficients of correlation of yield with date of 

 heading and date of maturity in the variety tests discussed in this 

 paper are shown in Table 18. 



TABLE 18. CORRELATION OF YIELD WITH DATES OP HEADING AND MATURITY IN 

 VARIETY TESTS OF BARLEY, OATS, AND WHEAT 



When a very high correlation exists between earliness and yield 

 it is likely that a character closely correlated with one may show a 

 high degree of correlation with the other, which might not be shown 

 were it not for the first correlation. For example, suppose earliness 



