Excised-leaf water status evaluation and associations in field-grown winter wheat

Abstract

Water status measurements of excised leaves have been proposed as screening criteria for drought resistance in cereal crops. This study was conducted to assess the utility of such measurements in a wheat breeding program, through evaluation of environment and genotype differences in excised-leaf water status and examination of associations with several other traits. Initial water content (IWC) and rate of water loss (RWL) of excised leaves, epicuticular wax content (EW), stomatal frequency (SF), flag leaf area (LA), plant height (HT), heading date (HD), grain yield (GY), and test weight (TW) were measured on 24 winter wheat (Triticum aestivum L.) genotypes grown near Fort Collins, CO, during 1986–1987 and 1987–1988 (F87 and F88, respectively: subirrigated environments) and near Bennett, CO, during 1987–1988 (B88: dryland environment). Differences among genotypes for IWC and RWL were significant for F87 and F88, and nonsignificant for B88. Combined analyses of variance showed significant differences among environments for IWC and RWL. Initial water content was less for B88 than for F87 and F88. Significant genotype × environment (G × E) effects for IWC and RWL suggested that selection for high IWC or low RWL in irrigated environments (F87 and F88) may not provide selections that respond similarly in dryland environments (B88). Correlations for B88 revealed only a small, positive correlation between IWC and GY (r = 0.49*). For F87 and F88, significant correlations were observed between IWC and SF (r = −0.57** and −0.78**), RWL and LA (r = 0.74** and 0.71**), RWL and HT (r = 0.63** and 0.57**), and RWL and HD (r = 0.71** and 0.57**). Neither IWC or RWL were correlated with EW in any environment. Correlations between RWL (subirrigated) and G Y and TW (dryland) suggested that selection for low RWL in irrigated environments could provide some GY or TW advantage in dryland environments, despite observed G × E interaction and lack of RWL differences under the dryland environment. Key words: Cuticular transpiration, Triticum aestivum L., leaf water loss, stomata, drought