214 



MAIZE 



CHAP, are inherited together. When one of such characters is present 

 v - in an individual, another character is almost certain to be 

 present which is correlated with it. These correlations may 

 be of several kinds; Webber (3) divides them into four groups, 

 which he has termed Environmental, Morphological, Physio- 

 logical, and Coherital. 



By environmental correlation he means to indicate relation 

 to physical conditions or environment, such as to soils of vary- 

 ing degrees of fertility. Such correlations include increase in 

 number of grains with increase in height of culm, etc. They 

 " are merely the expression for equality or conformity to con- 

 dition of luxuriance. Strictly speaking, these are not corre- 

 lated characters, and their consideration is of little or no value 

 to the breeder." 



He defines morphological correlations as those cases where 

 a variation in one character is the primary cause for variation 

 in another character, e.g. where the relationship between the 

 characters is similar to that which exists between size of germ 

 and oil-content of maize-grain. 



Physiological correlations include such cases as the reduc- 

 tion in yield of fruit and seed in inverse ratio to excess of 

 leaf-production, as in some races of tobacco, or of wood as in 

 the case of certain fruit-trees. 



Coherital correlations include "those characters which are 

 not related to each other in any direct or causal sense, but 

 which are inherited as single unit-characters". Such cases 

 include the naked grain of certain races of oat correlated with 

 large number of flowers in a spikelet. 



It is of practical importance to the breeder to understand 

 the correlations of the characters with which he deals. It is 

 essential to a proper selection of parent plants that he should 

 not only pick out those bearing good ears, but that he should 

 also study the habit of growth of the plant, its stem, leaf, and 

 flowers, for these have an important influence on the produc- 

 tion of good grain, and their precise relationships should be 

 accurately determined and defined. 



" As yield is the character of paramount importance, and 

 as this character can now be determined only by laborious 

 field tests, it is of the utmost importance that careful considera- 

 tion be given to plant characters that may be correlated to 



