Abstract

Water-use efficiency and its relationship to physiological and morphological characteristics was investigated using blue panicgrass (Panicum antidotale Retz.). Four clones which had been characterized previously as being seedling drouth tolerant and four as being seedling drouth susceptible were subjected to three levels of soil-moisture stress. A program-controlled environment was used to simulate climatic conditions of the arid southwestern U.S. Clones differed significantly in water-use efficiency. As soil-moisture stress increased water-use efficiency and dry matter production decreased. Dry weight, fresh weight, and total protein were significantly associated with water-use efficiency. The clones most efficient in water use had more vascular bundles in the leaves when compared with the least efficient clones. The amino acids (micromoles/mg) lysine, histidine, arginine, glycine, and alanine were significantly associated with water-use efficiency. A non-significant association was found between seedling drouth tolerance and water-use efficiency for the clones studied. Additional clones are being studied to elucidate further the relationships between these characteristics.

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