CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
WANGXiaoWei, DUFoLi, YANHongCai, LANGZhengDong, DANGZhiJuan, LIBaoChun, WANGJunCheng, MAXiaoLe, WANGHuaJun, ZHANGHong, YAOLiRong
【Objective】Drought is one of the key factors causing wheat yield reduction, and developing wheat germplasm with strong drought resistance is a major challenge in current wheat breeding. Spring wheat plays a crucial role in safeguarding national food security. Clarifying the drought resistance of spring wheat germplasm will provide a basis for the exploration of drought resistant genes and drought germplasm innovation in spring wheat.【Method】In this study, a total of 396 spring wheat varieties (lines) treated with drought stress were used to determine the relative water content of leaves, chlorophyll content and leaf area index et al during the grain filling stage, and also measure plant height, spike length, and effective tillers et al in the maturity stage, the drought resistance coefficient of each index was calculated. A comprehensive evaluation of drought resistance for each spring wheat variety (line) was conducted based on descriptive statistics, principal component analysis, membership function method, cluster analysis and correlation analysis. 【Result】Compared with the normal irrigation conditions, all indices of each spring wheat variety in the grain filling stage and maturity stage decreased under drought stress. Among them, plot yield, leaf area index, and biomass showed higher decreases, while chlorophyll content, spike length, and relative water content of leaves exhibited the lower decreases. Significant differences were observed in drought resistance among the different varieties (lines). Under drought stress, the variation coefficient of each relevant index ranged from 6% to 34%, while the variation coefficient of each index ranged from 5% to 34% under normal irrigation condition. Principal component analysis was performed on the drought resistance coefficients of 4 indices at the grain filling stage and 8 indices at the maturity stage, 6 principal components were extracted with a cumulative variance contribution rate of 78.07%. The comprehensive drought resistance coefficient (D value) was calculated using the membership function value, and cluster analysis was conducted based on the D value to classify the 396 spring wheat varieties (lines) into 5 categories, followed by inter-group variance analysis, we found that the spring wheat varieties (lines) with strong drought resistance showed the highest plot yield, and it had the lowest decrease. Meanwhile, correlation analysis between the D value and the drought resistance coefficients of 12 indices revealed that the number of spikelets, biomass, flag leaf area, and effective tillers were considered as the effective comprehensive evaluation indices for spring wheat drought resistance identification. In addition, there were highly significant positive correlations between the relative water content of leaves and plant height, effective tillers, number of spikelets, biomass, the internode length below spike and plot yield, the chlorophyll content exhibited a highly significant correlations with 1000-grain weight, and flag leaf area had a remarkable positive correlations with spike length and 1000-grain weight under normal irrigation conditions. However, under drought stress, there were highly significant positive correlations between the relative water content of leaves and biomass, plot yield and 1000-grain weight, the flag leaf area had a remarkable positive correlations with spike length and biomass. Which indicated a close relationship between drought resistance indices in the grain filling stage and key agronomic indices in the maturity stage for spring wheat. 【Conclusion】There were 20 spring wheat germplasm resources with strong drought resistance that were selected in this study, which showed the highest yield and the lowest yield reduction under drought stress, and the number of spikes, biomass, flag leaf area, and effective tillers could be considered as the effective comprehensive evaluation indices for spring wheat drought resistance identification.