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Differential adaptations of barley (Hordeum vulgare L.) and wheat (Triticum spp.) genotypes suggest that they be evaluated under multi-environmental conditions. The objectives of this study were to determine if small grain genotypes, bred for various moisture conditions, respond differently in terms of yield, water use, and rooting pattern to contrasting moisture conditions. Eight small grain genotypes were compared under a gradient of water from 89 to 404 mm (plus 254 mm of stored water) in a field study at Marana, AZ. A barley bred for low input conditions had greater root density in the subsoil and used moisture earlier in the season when compared to a high input barley (WestBred Gustoe). The cultivars bred for high input conditions required more water for optimum yield compared to those bred for low input conditions.

Tepary bean (Phaseolus acutifolius A. Gray) was grown in Tucson, Arizona during the summer rainy seasons of 1987 and 1988. Effects of water and nitrogen on growth, yield and yield components were evaluated in 1987. In 1988, effects of water and intercrop competition with Sonoran panicgrass (Panicum sonorum Beal) were evaluated. Total shoot biomass, seed yields and pod yields were significantly reduced by lack of applied water in both 1987 and 1988. Seeds pod⁻¹ were unaffected by lack of applied water in both 1987 and 1988 while mean seed weight was significantly reduced for rainfed treatments relative to irrigated treatments in 1987 but not in 1988. In 1987, addition of nitrogen had no significant effect on total shoot biomass, seed yield or yield components. In 1988, intercrop competition significantly reduced total shoot biomass, seed and pod yields of tepary bean. Seeds pod⁻¹ and mean seed weight were not affected by competition.

Differential adaptations of barley (Hordeum vulgare L.) and wheat (Triticum spp.) genotypes suggest that they be evaluated under multi-environmental conditions. The objectives of this study were to determine if small grain genotypes, bred for various moisture conditions, respond differently in terms of yield, water use, and rooting pattern to contrasting moisture conditions. Eight small grain genotypes were compared under a gradient of water from 89 to 404 mm (plus 254 mm of stored water) in a field study at Marana, AZ. A barley bred for low input conditions had greater root density in the subsoil and used moisture earlier in the season when compared to a high input barley (WestBred Gustoe). The cultivars bred for high input conditions required more water for optimum yield compared to those bred for low input conditions.

Tepary bean (Phaseolus acutifolius A. Gray) was grown in Tucson, Arizona during the summer rainy seasons of 1987 and 1988. Effects of water and nitrogen on growth, yield and yield components were evaluated in 1987. In 1988, effects of water and intercrop competition with Sonoran panicgrass (Panicum sonorum Beal) were evaluated. Total shoot biomass, seed yields and pod yields were significantly reduced by lack of applied water in both 1987 and 1988. Seeds pod⁻¹ were unaffected by lack of applied water in both 1987 and 1988 while mean seed weight was significantly reduced for rainfed treatments relative to irrigated treatments in 1987 but not in 1988. In 1987, addition of nitrogen had no significant effect on total shoot biomass, seed yield or yield components. In 1988, intercrop competition significantly reduced total shoot biomass, seed and pod yields of tepary bean. Seeds pod⁻¹ and mean seed weight were not affected by competition.

A pearl millet hybrid (Pennisetum americanum (L.) Leeke) and its two parents were evaluated for their photosynthetic rates, diffusive resistance, canopy temperature, transpiration rates, stomatal aperture and frequency, and growth responses to various irrigation levels. The experiments were conducted on Brazito sandy loam soil at The University of Arizona Campus Agricultural Center, Tucson, AZ in 1985 and 1986. A sprinkler was used to create water treatments. Photosynthetic rates were not significantly different among genotypes at each water level. Transpiration rate, diffusive resistance, canopy minus ambient temperature, and photosynthetic rate were all significantly related to water treatments with correlation coefficients .ranging from 0.91 to 0.98. Under water stress, the female transpired more, exhibited lower diffusive resistance and had a cooler canopy compared to the hybrid and male parent. Based on these characteristics, the female seemed to expend more energy on heat dissipation than yield improvement. Water stress reduced stomatal aperture but increased stomata! frequency. The hybrid had significantly higher stomatal frequency at all water levels and smaller aperture between 63 and 125 mm irrigation levels. Dry matter, leaf area, leaf area index, and plant height were also reduced by water stress. In general, the hybrid and the male parent produced significantly more dry matter and were significantly taller than the female. The female parent had significantly higher leaf area and leaf area index late in 1986. Grain yield was reduced by water stress. Both years, the female grown under optimum moisture conditions had approximately half the grain yield as compared to the male and the hybrid. The major components contributing to the higher grain yield of the hybrid and male were larger panicles and more productive tillers.