CORRELATION AMONG QUANTITATIVE CHARACTERS IN 
MAIZE 1 
By J. H. Kempton 
Assistant Plant Breeder , Office of Biophysical Investigations , Bureau of Plant 
Industry, United States Department of Agriculture 
Varieties of maize differ greatly in general size and in the length of time re¬ 
quired to produce a crop. As a rule, the large varieties require a longer growing 
period and produce a greater yield than the small varieties. 
The breeder, in producing a type of maize for special conditions, often is con¬ 
fronted with the task of combining the characters of high productivity with 
earliness and therefore it is desirable to know to what extent the various characters 
of size and season are correlated among themselves. 
If intervarietal correlations were calculated it would be found that the char¬ 
acters of size and season were very closely associated, but such correlations would 
afford little basis for predicting the facility with which such combinations could 
be dissolved through hybridization. With many combinations there are, of 
course, physiological limitations which can not be surmounted, but a consideration 
of the varieties in existence shows that physiological limitations permit a wide 
range of combinations. 
It has been shown that size characters in maize are inherited and that the 
mode of inheritance can be explained in accordance with Mendelian principles 
by hypothecating numerous stable heritable elements or factors. 2 Since these 
factors are distributed among 10 chromosomes it follows that numerous genetic 
correlations among size characters are to be expected, but while such correlations 
increase the difficulty of making new combinations they seldom are insurmount¬ 
able. 
Correlations among various characters of maize have been studied by several 
investigators, chiefly in searching for a criterion of selection within a variety. 3 , 4 , 5 
Such studies have shown an almost complete independence of the characters of 
the ear with subsequent yield or other size characters, but since they were made 
within a single variety in each case they do not afford a secure basis for predicting 
complete freedom of recombination in hybrids between diverse forms. 
MATERIAL 
The present investigation was undertaken with a view to measure the correla¬ 
tions among certain quantitative characters in hybrids between varieties of 
maize offering the maximum size differences. 
As the diminutive parent the writer has used the well-knowm Tom Thumb 
variety of pop corn which, excluding abnormal dwarf forms, probably is the 
i Received for publication June 27, 1924—issued November, 1924. 
1 Emerson, R. A., and East, E. M. the inheritance of quantitative characters in maize. Nebr. 
Agr. Exp. Sta. Research Bui. 2, 120 p., illus. 1913. 
» Ewing, E. C. correlation of characters in corn. N. Y. Cornell Agr. Exp. Sta. Bui. 287, p. 67- 
100, illus. 1910. 
< Love, H. H. the relation of certain ear characters to yield in corn. Ann. Rpt. AmerJ 
Breeders’ Assoc. 7 : 29-40. 1912. 
* Love H. H., and Wentz, J. B. correlation between ear characters and yield in corn. Jour, 
Amer. Soc. Agron. 9 : 315-322. 1917. 
Journal of Agricultural Research, 
Washington, D. C. 
( 1095 ) 
Vol. XXVIII, No. 11 
June 14, 1924 
Key No. G-496 
