Agronomic Characteristics and Grain Yield of 30 Spring Wheat Genotypes under Drought Stress and Nonstress Conditions

Drought is an important environmental stress limiting wheat (Triticum aestivum L.) productivity in water limited regions. Our aim was to understand the relationships between target agronomic traits and grain yield (GY) responses to drought, and to prioritize genotypes for high yield under different water conditions. Thirty spring wheat genotypes were evaluated over 2009 and 2010 for GY and agronomic traits under T1 (non-irrigated), T2 (50% evapotranspiration [ET] irrigated), and T3 (100% ET irrigated) irrigation regimes. Drought stress caused noticeable fewer days to physiological maturity (PMD), shorter plant height (HT) and exposed peduncle length (EPL), smaller grain volume weight (GVW), higher grain protein content (GPC), smaller kernel weight (KW) and kernel diameter (KD), and less GY. All target traits were significantly correlated with GY except for days to heading (HD) in 2010. Selected traits for 2009 (PMD, HT, GVW) and 2010 (PMD, HT, GPC) together explained 82 and 93% of the total phenotypic variation of GY, respectively. Selected genotypes were classified into four types based on their agronomic and yield performance across three irrigation regimes. High-yield (HY) genotypes IDO599, Alturas, and IDO702 had better agronomic performance and produced high GY across different water conditions; drought-resistance (DR) genotypes Agawam, McNeal, and Alpowa exhibited drought resistance in target traits and produced higher GY than other genotypes under drought. Preliminary results indicate that GY could be estimated on the basis of agronomic performance including PMD, HT, GVW, and GPC, and selecting HY and DR genotypes for water limited environments may be important for improving yield productivity.