Evaluation of Techniques for Screening for Drought Resistance in Wheat¹

Abstract

Three techniques were evaluated for screening for drought resistance in rainfed and irrigated Triticum aestivum L. em Thell., and T. turgidum L. var. durum field plots, viz., leaf diffusive resistance as measured with an autoporometer, leaf temperature as measured with a hand‐held infrared thermometer, and drying rate of excised leaves. Eight durum and 10 hexaploid cultivars of diverse origin were grown in each of two years. Yields under rainfed relative to irrigated conditions were used to characterize the drought resistance of the cultivars. Neither diffusive resistance measurements nor leaf temperature were suitable screening techniques since differences between cutivars were not detected. There were marked differences in leaf temperatures between the rainfed and irrigated environments. Cultivar differences were detected in excised leaf water loss rate. Water retention capability was greatest early in the season, and dropped markedly after anthesis. The drought‐hardy durum cultivar Pelissier had the best water retention capability. Progeny of a Pelissier ✕ Hercules cross showed a range of retention capabilities between the parental values. Visual rating of excised leaves identified the genotypes with superior water retention capabilities. It was concluded that measurement of excised leaf water retention capability showed the most promise of the three techniques evaluated