EXPERIMENTS IN FIELD PLOT TECHNIC 39 



tition in this test are probably accounted for by the fact that the va- 

 rieties differed very widely in varietal type and in yield. Differences 

 of as much as 17 days in date of heading, 13 days in date of maturity, 

 and almost 200 per cent in yield, were involved. The correlations de- 

 termined between competition and relative date of heading, date of 

 maturity and yield, are shown in Table 16. 



TABLE 16. CORRELATION OF COMPETITION WITH VARIOUS CHARACTERISTICS IN 



OATS VARIETY TEST 1921. 



Character Mean difference be- Coefficient of correlation 



tween competing with competition 



varieties 



Date of heading 4.8 days .648 .060 



Date of maturity 4.1 days .860 .028 



Yield 51.1% +.484 .082 



A remarkably high negative correlation between date of maturity 

 and competition is shown. The negative correlation between date of 

 heading and yield is also quite high, while the positive correlation be- 

 tween yield and competition is barely significant. In this test, in which 

 extreme differences in time of maturity occurred, the early-maturing 

 varieties had a very distinct advantage in competition with the later 

 varieties. Earliness was very closely correlated with yield in the oats 

 variety test of this season, the coefficient of correlation for date of 

 heading and yield being .750 .052 and that for date of maturity and 

 yield being .894 .024. Considering the close correlation of earliness 

 and yield, and the relatively low correlation of yield and competition, 

 it would seem that the latter may be merely a by-product of the rela- 

 tion of earliness to competition. Since the early varieties were the 

 leaders both in competition and in yield, some correlation of yield and 

 competition is inevitable. 



In the oats strains test of 1921 Kherson and Red Rustproof strains 

 were alternated and both a Kherson and a Red Rustproof check were 

 grown. In most cases therefore the competing border rows repre- 

 sented these two varieties, though in some cases two Red Rustproof 

 or two Kherson plots occurred together, as is shown in the planting 

 plan in figure 5. The effects of competition in this plot were quite 

 distinct, as is to be expected, though they were not so extreme as in 

 the oats variety test discussed above, which was located on the same 

 field. The average yield of border rows differed from the average yield 

 of interior rows by 11.76 per cent. The mean coefficient of compe- 

 tition was 23.85 per cent. 



When we exclude the competition between the three strains not 

 true to name and the strains adjacent to each, that between the Kher- 



