396 



Journal of Agricultural Research 



Vol. IV, No. s 



The results are summarized in Table II, the female parent being given 

 first in each instance. In this table is included also the average water 

 requirement of the two parents, together with the ratio of the water 

 requirement of the hybrid to that of the parental mean. The divergence 

 of the parents — i. e., the ratio of their water requirements — is also given 

 in the last column of the table. 



Table II. — Water requirement of hybrid and parent strains of corn 



Year and parent strain. 



1912 



China 



Laguna 



China 



Esperanza 



1913 



China 



Hopi 



China 



Teosinte 



1914 



Algeria 



China 



Budapest 



Joaquin 



Budapest 



Pima 



Joaquin 



Pima 



Water requirement based on dry matter. 



Parent strain. 



Observed. Mean. 



3iS±7 

 295±6 



3i5±7 

 239±3 



4i5±4 

 35o±8 

 4i5±4 

 39o±ii 



33i±4 

 338±6 

 345 ±4 

 368 ±9 

 345 ±4 

 365 ±7 

 368 ±9 

 36S±7 



305 ±5 

 277±4 



} 383±5 



I 403 ±6 



} 335±4 



} 357±5 



I 355±4 



} 367±6 



Hybrid. 



Observed. 



289±4 



250±2 



345±3 

 376±4 



347 ±5 

 365±4 

 389 ±5 

 389±9 



Ratio of 



hybrid to 



parental mean. 



2C 



a+b 



0. 95 ±. 02 

 . 90±. 01 



. 90±. 02 

 .93 ±.02 



1. 04±. 02 

 I. 02 ±. 02 

 I. loi. 02 

 I. o6±. 03 



1.07 

 1.32 



I. 19 

 I. 07 



I. 02 

 I. 07 

 I. 06 

 I. 01 



Reference to Table II will show that the parents of the hybrids grown 

 in 1 91 2 and 191 3 differed in water requirement much more than the 

 parent strains employed in 191 4. Each first-generation hybrid of maize 

 grown during the first two years gave a water requirement ranging from 

 5 to 10 per cent below the mean of its parents. All the maize hybrids 

 grown in 1914 gave a water requirement from 2 to 10 per cent above the 

 mean of the parents. The results of the third year are therefore opposed 

 in direction to those obtained during the first two years. 



The parents of the hybrids used in 191 2 and 191 3 also showed much 

 greater divergence in water requirement than those employed in the 1914 

 measurements. The question therefore arises as to whether the diver- 

 gence of the parents may not be a factor in determining the relation of 

 the water requirement of the hybrid to the parental mean. 



