Field Identification of Drought Tolerant Wheat Genotypes Using Canopy Vegetation Indices Instead of Plant Physiological and Biochemical Traits

Abstract

When subjected to water stress, the plant itself will respond physiologically, biochemically and morphologically, and the response degree may be different among different wheat genotypes. Remote sensing technology can effectively monitor these traits under different environmental conditions, but whether it can be used as a preliminary screening tool for the drought tolerance of a large number of genotypes is still lacking relevant reports. This study aims to characterize the physico-biochemical trait performance of the ten wheat genotypes with different genetic backgrounds in response to soil moisture variation, and to screen stable drought-tolerant genotypes obtained using multivariate techniques and spectral measurement techniques. Traits associated with drought stress were assessed in ten wheat genotypes, including plant biophysical parameters, drought tolerance parameters, as well as various vegetation indices (VIs). The results showed that all of the studied traits differed significantly among the two water conditions regardless of the wheat genotypes1. A wide variation among all of the tested genotypes, according to the morphophysiological traits and drought resistance parameters, was due to drought stress on the basis of which they were clustered into three groups using principal component analysis (PCA) and the hierarchical clustering method (HCA). The clustering results indicated that genotypes with a higher grain yield, stress tolerance index (STI), drought index (DI), and drought tolerance coefficient (DC) were identified as drought-tolerant genotypes. Simultaneously, drought resistance parameters, such as STI and DI, correlated strongly with the normalized difference water index (NDWI) and the red edge chlorophyll index (CIred edge), so they are recommended as rapid indicators for field-tolerance genotype identification. Heatmap analysis from various VIs to screen wheat genotypes showed similar results to multivariate techniques, that is, genotypes Luohan-19, Luohan-22, and Jinmai-47 were identified as drought-tolerant genotypes. In conclusion, the VIs, drought tolerance indices, and multivariate data analysis have similar performance and can effectively screen drought tolerant wheat genotypes to adapt to short-term drought in the North China Plain.

Keywords: Winter wheat, Drought tolerance, Physico-biochemical traits, Vegetation indices, Heatmap analysis