Evaluation of Grain Yield and Three Physiological Traits in 30 Spring Wheat Genotypes across Three Irrigation Regimes

Accurate field evaluation of yield-related physiological traits is critical for selecting high yield and drought resistance in wheat (Triticum aestivum L.). To characterize grain yield and three physiological traits for 30 spring wheat genotypes, field experiments with three irrigation regimes were conducted in 2009 and 2010 field seasons. Our study suggests that Feekes 11.2 is the optimal stage to evaluate flag leaf senescence (FLS) and canopy temperature (CT) when making selections for high grain yield and drought resistance among wheat genotypes. Flag leaf carbon isotope discrimination (CID) was positively correlated with grain yield, whereas FLS and CT were negatively correlated with grain yield. The three traits together explained 92% of the total phenotypic variation of grain yield. Selected genotypes were classified into four groups based on yield performance across irrigation regimes. High-yield genotypes IDO599, 'Alturas', and IDO702 produced high grain yield across different water conditions; drought-resistant genotypes 'Agawam', 'McNeal', and 'Alpowa' produced higher grain yield under the nonirrigated regime. High yield of those genotypes was contributed by good performance of physiological traits such as late FLS, great CID, or low CT or combinations of these traits. Preliminary results indicate that using physiological traits to estimate yield performance can be effective, and selecting suitable genotypes for different water environments may be crucial for improving yield productivity.