Variation and Correlation of Oats — Part II 215 



are comparable only in so far as the conditions of growth are com- 

 parable. 



The fourth division of this study deals with the effect of different degrees 

 of crowding on biometrical constants of oats. Oat plants grown in very 

 crowded conditions produce but one culm to a plant, but, as more room 

 is given, more than one culm are produced by many plants. The develop- 

 ment of plants in most characters is greater in less crowded than in more 

 crowded conditions. Variability decreases with increase in crowding 

 for yield, number of kernels, number of spikelets, and breaking strength 

 of straw; but for height the least variability occurs when 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 correlations produced by more crowded conditions, 

 but there is sometimes a decrease beyond a certain degree of crowding. 

 It has been shown that environmental conditions may influence the 

 degree of correlation of certain characters to a marked extent. Such 

 conditions of environment may make of no significance the so-called 

 varietal and other differences obtained by several investigators. 



ACKNOWLEDGMENTS 



The work described in this memoir was done in the Laboratory of the 

 Department of Plant-Breeding of the New York State College of Agri- 

 culture at Cornell University. The plants used were grown on the 

 experimental grounds of the department. The writer wishes to acknowl- 

 edge his appreciation of the many helpful suggestions and the encourage- 

 ment given by Dr. H. J. Webber, and, in the biometrical work, by Dr. 

 H. H. Love. The assistance of Mrs. C. E. Leighty in much of the bio- 

 metrical work is greatly appreciated. 



LITERATURE CITED 



Atkinson, Alfred 



1912 A study of the correlation of characters of wheat. Thesis for 

 degree of M. S. in Agr., Cornell LTniversity, 1912. (Unpub- 

 lished.) 



Davenport, Eugene 



1907 Principles of breeding, p. 1-727. 



