38 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN 49 



was 18.85 per cent. Correlations were determined for competition and 

 relative yield, date of maturity, date of heading, and height in this 

 test. The coefficients of correlation thus determined are shown in 

 Table 14. 



In this case, as in the wheat variety test of the preceding season, 

 dates of heading and maturity were correlated negatively and yield 

 was correlated positively with competition. The coefficients of correla- 

 tion were materially lower, and in fact are hardly significant. It is in- 

 teresting that in this case height was correlated more closely with 

 competition than were either earliness or yield. In this season again 

 earliness was correlated to some extent with yield, the coefficients of 

 correlation, for date of heading and yield being .331 .062 and for 

 date of maturity and yield .419 .057. 



In the wheat mixture test of 1921 the varieties were grouped 

 roughly in respect to earliness, and in only three cases was there a 

 greater difference than two days in heading or maturity between ad- 

 jacent varieties. The rows in this test ran north and south. The 

 conditions may be considered favorable in this test for the reduction 

 of competition. Nevertheless the average yield of border rows dif- 

 fered from that of interior rows by 10.07 per cent and the mean co- 

 efficient of competition was 14.28 per cent. The coefficients of correla- 

 tion determined for competition and date of heading, date of maturity, 

 and yield, are shown in Table 15. 



TABLE 15. CORRELATION OF COMPETITION WITH VARIOUS CHARACTERISTICS IN 

 WHEAT MIXTURE TEST 1921. 



Character Mean difference be- Coefficient of correlation 



tween competing with competition 



varieties 



Date of heading 1.2 days .514 .083 



Date of maturity 0.8 days .613 .070 



Yield 19.2% +.554 .078 



In this test significant negative correlations between competition 

 and dates of heading and maturity and a significant positive correla- 

 tion between competition and yield are shown. The tendency for 

 early, high-yielding varieties to profit by competition was about as 

 strong as in the wheat variety test of the preceding season, though the 

 extent of competitive effect was considerably reduced. 



The effects of competition in the oats variety test in 1921 were 

 extreme. The yields of border rows differed by 16.74 per cent, on 

 the average, from the yields of interior rows, and the mean coefficient 

 of competition was 39.15 per cent. The extreme effects of compe- 



