32 VALUE OF FIRST-GENERATION HYBRIDS IN CORN. 



That the utihzation of first-generation hybrids will be found of 

 special value in the drier parts of the country was clearly indicated 

 by the behavior of the hybrids described in these pages. 



The season during which these hybrids were grown was one of 

 exceptional drought, affording an excellent opportunity for observing 

 the (Irought-resisting ability of the different strains and their hvbrids. 

 The rainfall at Washington, D. C, for April, May, and June was 

 slightly below the average, and for July and August it was 4.07 

 inches, less than one-half the normal. 



The series included varieties from localities with such extremes of 

 climate as obtain in the plateau region of Mexico and the moist 

 Tropics of the lowlands of Central America. While the differences 

 between the varieties in their ability to withstand drought were 

 obvious, the most striking differences of this kind were between the 

 hybrids and the pure strains. Almost without regard to the nature 

 of the parents the hybrids remained dark green and vigorous when 

 nearly all of the pure strains were giving evidence of the lack of mois- 

 ture by their curled leaves and yellow color. This ability to with- 

 stand drought may have been a factor in the increased yields which 

 the hybrids produced. 



Experiments are being made with a series of hybrids in western 

 Kansas and the dry Southwest with the idea of learning which crosses 

 will prove best suited to these extreme conditions. 



Experiments at the Virginia Agricultural Experiment Station 

 indicate that first-generation hybrids may be found to withstand 

 excessive moisture as well as drought. Wliile the crosses were 

 apparently inidertaken with the idea of establishing hybrid varieties, 

 the results so far as reported apply only to the first generation. 



The native varieties that were crossed with the western corns have developed, three 

 or four good strains, and out of some 350 samples tested here this j^ear none have stood 

 the wet season and made as good yields as the improved strains obtained by crossing 

 pure-bred western corn with our best native varieties. o 



Associated with the general increase in vigor in first-generation 

 hybrids a certain measure of disease resistance may naturally be 

 expected. Many plant diseases that are unable to attack vigorous 

 plants are able to do serious damage to weaker varieties or to plants 

 that are weakened by adverse conditions. The ability of the hybrids 

 to resist drought might at the same time ])rotect them against disease. 



In the case of the corn smut, which was the only disease that 

 affected any of the experiments, this factor of disease resistance does 

 not appear to apply^ for the attacks of the smut do not seem to 



« Vanatter, Phares O. Annual Report, Virginia Agricultural Experiment Station, 

 1906, p. 55. 

 191 



