392 Journal of Agricultural Research voi. iv, No. s 



MAIZE HYBRIDS 



In order to make a satisfactory comparison of the water requirement 

 of a hybrid with that of its parents, it is necessary to have the plants 

 growing under as nearly identical conditions as possible. Each deter- 

 mination includes, therefore, the measurement not only of the water re- 

 quirement of the hybrid but of each parent as well. The work can, of 

 course, be lessened somewhat by the employment of the same parent in 

 more than one combination when such material is available. 



The maize hybrids grown in 191 2 and 191 3 were all from the same 

 female parent, a Chinese type.^ This is a peculiar com with a waxy 

 endosperm, received by the Office of Foreign Seed and Plant Introduc- 

 tion, Bureau of Plant Industry, from Shanghai, China. Its water 

 requirement compared with other varieties of maize is relatively high. 

 Various hybrids of this variety were used each year, so that the water 

 requirement of the China type was measured three years in succession. 

 It will be seen that its water requirement in 191 3 was much higher than 

 during the two other years. Eleven other species of plants grown at 

 Akron during 191 2 and 191 3 showed a similar increase in water require- 

 ment in 1 91 3, attributable to climatic differences in the two seasons.' 

 The variation in water requirement with different seasons does not enter 

 into the present discussion, since only strains that were grown together 

 during the same season are compared. 



Of the other varieties tested, Laguna is a Mexican variety grown 

 extensively in Texas, where it has a reputation for drought resistance. 

 Esperanza is a hairy Mexican variety {Zea hirta Bonifous) introduced by 

 the Office of Crop AccUmatization and Adaptation Investigations. Hopi 

 is a dwarf variety grown by the Hopi Indians of Arizona, and Pima is a 

 soft com grown by the Pima Indians at Sacaton, Ariz. Algeria is a 

 slate-colored pop com the seed of which was imported from Algeria but 

 which came originally from Morocco.^ Joaquin is an American soft com 

 from Bradford Island, San Joaquin River, Cal. Budapest is a Hungar- 

 ian variety of pop com. 



The results of the water-requirement measurements for the individual 

 pots are given in Table I, together with the mean for each series. Six 

 pots were employed in each series in 191 2 * and 1913 and five pots in 

 1 9 14, which affords a basis for computing the probable error of the mean 

 value obtained. 



1 Collins, G. N. A new type of Indian com from China. U. S. Dept. Agr. Bur. Plant Indus. Bui. i6i, 

 30 p., 2 pi. 1909. 



2 Briggs, L. J., and Shantz, H. L. Relative water requirement of plants. In Jour. Agr. Research, v. 3, 

 no. I, p. s4- 1914. 



3 Collins, G. N. The value of first-generation hybrids of com. U. S. Dept. Agr. Bur. Plant Indus. Bui. 

 191, p. 25. 1910. 



and Kempton, J. H. Effects of cross-pollination on the size of seed in maize. In U. S. Dept. 



Agr. Bur. Plant Indus. Circ. 124, p. 10. 1913. 

 * With the exception of the Esperanza series, which included only 4 pots. 



