Aug. 16, 191S 



Hybridization and Water Requirement 



397 



If we represent the water requirement of the less efficient parent by a, 

 the more efficient parent by b, and the hybrid by c, then the divergence 



of the parents may be represented by the ratio -7, and the divergence of the 

 hybrid from the mean of its parents by the ratio 



a + b 



These ratios are 



given in Table II. Plotting these values for the eight hybrids under 

 discussion, we obtain a graph of the form given in figure i. This graph 



vz 



106 



I04 





IPO 



.96 



66 



too 



104 



1.08 



1.16 



L20 



U8 



15^ 



1^6 



Fig. I. — Graph showing relation between the parental divergence (v) and the hybrid divergence from 

 the parental mean f -tt ) > where a= water requirement of less efBcient parent; 6= water requirement 

 of more efficient parent; c= water requirement of hybrid. 



indicates a correlation between the divergence of the parents and the 

 divergence of the water requirement of the hybrid from the parental 

 mean. There are two outstanding points on this graph, both associated 

 with Budapest pop corn, which in both hybrids is the more efficient parent. 

 If the water requirement of Budapest variety were slightly increased, the 

 points would tend to approach the graph. On the other hand, four of the 

 eight hybrids under consideration have approximately the same parental 

 mean. Therefore, while the data indicate the existence of a relationship 

 between parental divergence and hybrid divergence, this relationship 

 can be expressed quantitatively only by the use of statistical methods 

 which require many more measurements than are now available and more 

 than the practical importance of the subject would justify at this time. 



