212 Clyde E. Leighty 



Yield increases slightly in its correlation with height as crowding in- 

 creases up to a certain point, beyond which there is a gradual decrease 

 in correlation. When yield is correlated with length of head, the differ- 

 ences are so small that definite conclusions cannot be drawn. Degrees 

 of crowding have little effect on the correlation between yield and number 

 of kernels. The same is true for yield and number of spikelets. There is a 

 sUght tendency shown for the correlation between jaeld and average weight 

 of kernels to increase as crowding increases. There is a decided and 

 significant increase in correlation between yield and number of kernels 

 per spikelet as crowding increases. It seems that, up to a certain point, 

 as crowding increases the correlation between yield and diameter of straw 

 increases, and that beyond this point there is a decrease. There is an 

 increase in correlation between yield and breaking strength of straw 

 with increase in crowding, but a limit is reached, beyond which there is 

 a decrease. Yield and weight of straw are highly correlated in the culms 

 of oat plants, and the correlation is increased to a slight extent by crowd- 

 ing up to a certain point, beyond which there is a decrease. The diameter 

 of straw is highly correlated with the breaking strength, but the least 

 correlation exists when the crowding is least. 



In every case when significant differences exist in the correlations 

 between characters in plants grown under different conditions of crowding, 

 there is an increase in correlation produced by more crowded conditions. 

 In no case is the coefficient of correlation for the least crowded condition 

 the largest, although the differences are often very small. There is, 

 however, sometimes a decrease in correlation beyond a certain degree 

 of crowding, in which case the coefficient for the intermediate degree of 

 crowding is the highest. 



It has been shown by this study that environmental conditions may 

 influence the degree of correlation of certain characters to a marked 

 extent. Such conditions may make of no significance the so-called varietal 

 and other differences obtained by several investigators. 



GENERAL DISCUSSION AND CONCLUSION 



This study of oats has been taken up under four heads, as was out- 

 lined at the beginning of the paper. Various data have been presented 

 and discussed under each of these heads, and summaries and conclusions 

 have been made at the end of each division . The study has been pursued 



