Understanding the responses of two wheat genotypes to individual and combined drought and heat stress during reproductive and grain filling stages
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Abstract
Drought and heat stress are the most devastating environmental stresses affecting wheat growth, development, and grain yield. Among all the phenological stages, reproductive and grain-filling stages are the most vulnerable stages results in significant yield loss. However, limited research has been conducted to examine the combined effects of both the stresses on wheat particularly at reproductive and grain filling stages. Therefore, the present study aimed to understand the response of wheat genotypes to individual and combined effect of drought and heat stress and to analyse the impact of such stresses on reproductive structures, yield and yield components. For this purpose, two genotypes (Gregory and Lincoln) were evaluated under control (CON), heat stress (HT), drought stress (DRT), and combined drought and heat (DRTHT) stress at the glasshouse facility at The University of Melbourne, Australia. Results revealed significant differences among treatments for floret fertility, pollen viability, pollen tube germination, chlorophyll content, leaf senescence, plant height, biological yield, grain yield and harvest index. Significant differences were also observed between genotypes for pollen viability, pollen tube germination, chlorophyll content and biological yield, whereas, non-significant for floret fertility, leaf senescence, plant height, yield and yield components. Overall, the stress treatments negatively affected all the traits under studied, where, combined effect of drought and heat stress was found to be more severe and intense on all the traits rather than their individual effects. Among genotypes, Gregory performed better than Lincoln for most of the traits under studied showing its tolerance to individual and combined effects of drought and heat stress. Identification of stress tolerant wheat genotypes may be useful for sustainable wheat production in areas prone to changing climatic conditions. Moreover, the stress tolerant genotype can be used in future breeding programs for variety development and genetic improvement of different wheat genotypes.
Keywords: Combined drought and heat stress; Drought stress; Grain filling stage; Heat stress; Reproductive stage; Wheat