Water-use efficiency of seven cultivars of alfalfa (Medicago sativa L.).

Abstract

Two experiments were conducted in a greenhouse environment at Tucson, Arizona to determine the water-use efficiency of five cultivars and two experimental lines of alfalfa (Medicao sativa L,) at both the seedling and mature stages of plant development. Another experiment was conducted to determine differences in water-use efficiency among genotypes within the cultivars Mesa-Sirsa and Ladak. Significant differences were found in water-use efficiency among cultivars in both the seedling and mature stages of plant development. Cultivars did not maintain their rank between the stages of plant development in either water-use efficiency or dry matter production. Plants of Mesa-Sirsa transpired more water than those of other cultivars in both experiments. Significant differences were found among plants of different cultivars in dry forage and transpired water in the seedling stage; however, no significant differences for these factors were found among cultivars in the mature stage of plant development. More variatior in water-use efficiency was found within cultivars than was found among cultivars. Transpired water, dry forage production, stomate density, leaflet to stem and petiole ratios, and percentage protein were each correlated with water-use efficiency.