Evaluation of 14 morphological, yield-related and physiological traits as indicators of drought tolerance in Chinese winter bread wheat revealed by analysis of the membership function value of drought tolerance (MFVD)

Drought is a worldwide problem seriously influencing bread wheat (Triticum aestivum L.) production. The capability of 14 morphological, yield-related and physiological traits as indicators for identifying drought tolerant genotypes in wheat was evaluated among 90 wheat accessions under water-stressed (WS) and well-watered (WW) conditions in this study. The membership function value of drought tolerance (MFVD) of 14 traits was used as a comprehensive index for evaluation and selection of wheat drought tolerance. Ninety wheat genotypes from major wheat production areas of China were used as materials in an experiment by two factors split-plot design with two replications in a rainout shelter. Water treatments were as the main plots and genotypes were as the subplots. The mean values of all 14 traits decreased under water-stressed condition, among the 14 traits, BYPP, DSL, GYPP, SC and TR decreased >25%. This suggested that these 5 traits were more sensitive to water stress. The broad sense heritability of morphological traits (PH, UIL, DSL and SL) was relatively high and that of yield-related traits (BYPP, GYPP, TKW, SN and GNPS) was medium, while the broad sense heritability of physiological traits (PR, TR, CI, SC and SPAD) was low. Five accessions with highly drought tolerance were screened according to MFVD and could be applied for drought tolerance improvement in wheat. Correlation analysis revealed that the wheat drought tolerance was highly significantly and positively correlated with variations of 11 traits under two water treatments (P < 0.001). Regression models built based on MFVD indicated that the variation of drought tolerant coefficient of 5 traits of grain yield per plant, transpiration rate, plant height, uppermost internode length and spike length could explain about 91.6% of total variation. Therefore these five traits could be used as a combination to screen wheat germplasm or lines for drought tolerance in wheat breeding program.