Evaluating the Waterlogging Tolerance of Wheat Cultivars during the Early Growth Stage Using the Comprehensive Evaluation Value and Digital Image Analysis

Abstract

The accurate and efficient screening of waterlogging-tolerant cultivars is an effective way to mitigate waterlogging damages. An experiment was conducted to evaluate the performance of 28 wheat varieties mainly planted in the middle and lower reaches of the Yangtze River, China, under control and waterlogging conditions. When the 15-day waterlogging that was initiated at the third-leaf stage was completed, the aboveground dry weight, plant height, leaf number on main stem, culm number, leaf area, and SPAD readings of wheat seedlings were significantly decreased by 14%, 11%, 6%, 13%, 14%, and 15% compared with the control treatment (maintaining approximately 80% of field capacity), respectively. The results showed that the percentage reductions in the dry weight and leaf area under stress accurately represented the influence of the majority of the measured agronomic traits and were significantly negatively correlated with the respective dry weight and leaf area of different cultivars under waterlogging. This suggests that dry weight and leaf area can be used as agronomic traits for screening waterlogging-tolerant cultivars. The comprehensive evaluation value of waterlogging tolerance (CEVW) was closely related to the percentage reduction in dry weight, plant height, culm number, leaf area, and SPAD reading. The range of CEVW was 0.187–0.819, indicating a wide variation in the waterlogging tolerance of the wheat cultivars. Comparing the top-view images, the phenotypic texture parameters (dissimilarity, homogeneity, and angular second moment (ASM)) extracted from the side-view images better reflected the dry weight, plant height, and leaf area under different water treatments. The percentage reduction in ASM had the strongest correlation with CEVW (root mean square error = 0.109); thus, the ASM is recommended as a suitable phenotypic parameter to evaluate waterlogging tolerance. The present results provide references for the rapid and intelligent screening of waterlogging-tolerant wheat cultivars, but future studies need to consider the stress evaluation of the adult plants.