Differences in Drought Resistance between Two Corn Hybrids. II. Component Analysis and Growth Rates
1987
Lorens, G. F. | Bennett, J. M. | Loggale, L. B.
Relatively little research has been conducted to evaluate differing responses to water stress among genotypes of the same species. The objective of this study was to identify differences in growth and development of plant parts resulting from water stress imposed on two corn (Zea mays L.) hybrids that had been observed to differ in their sensitivity to water stress. During 1983 and 1984, two corn hybrids (Pioneer Brands 3192 and 3165) were subjected to three water management treatments: optimal irrigation, rainfed, and stress during vegetative (1983) or early reproductive (1984) growth. Growth analysis revealed few differences between hybrids for leaf area index, and crop and seed growth rates when well-watered or stressed during vegetative growth, except that hybrid 3192 showed more rapid early growth. When well-watered, grain yield of hybrid 3192 was the same (1983) or higher (1984) than grain yield of hybrid 3165. However, the two hybrids differed in their ability to resist severe water stress. The greater grain yield of hybrid 3165 in the rainfed treatment was associated with relatively smaller reductions in crop growth rate, total biomass accumulation, seed number, effective filling period, and harvest index with stress when compared to hybrid 3192. The greater crop growth rate and final biomass and grain yield of hybrid 3165 during severe stress most likely resulted from the maintenance of higher leaf water and turgor potentials and lower leaf diffusive resistances that were apparently mediated by higher root length densities in deeper zones of the soil profile as described in a companion paper.
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