Screening Indexes for Drought Resistance of Seven Winter Wheat Cultivars at the Grain-filling Stage

This paper evaluated drought resistance of wheat using physiological indexes and agronomical traits, with 'Xinong979’ and six other winter wheat (Triticum aestivum L.) cultivars taken as test materials. The comprehensive resistance of drought resistant coefficients of the investigated indexes was conducted with principal components, and the correlation between comprehensive indexes (D) and drought resistance indexes (DRI) was studied. Results showed that: (1) Compared with the contrast, superoxide dismutase (SOD) activities, catalase (CAT) activities, relative conductivity, malondialdehyde (MDA) content, proline content, soluble sugar, and intercellular CO₂ concentration (C_i) increased at different levels, while root vigor, net photosynthesis rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), plant height, internode length below spike, flag leaf area, ear length, spikelet number and grains per ear decreased. The trend of peroxidase (POD) activities and soluble protein content were different among the cultivars. (2) Based on the comprehensive indexes (D), the seven tested cultivars were divided into three groups. ‘Jinmai47’ and ‘Xiaoyan22’ belonged to the high drought resistance group, ‘Aikang58’, ‘Xinong979’ and ‘Xinong509’ belonged to the medium drought resistance group, and ‘Zhengmai366’ and ‘Zhengmai9023’, belonged to the low drought resistance group. (3) At two different drought stress levels, the comprehensive indexes (D) were significantly correlated with the drought resistance indexes (DRI) (r = 0.768, 0.808; p < 0.05).