ELUCIDATING THE EFFECT OF HEAT AND WATER DEFICIT STRESS COMBINATION IN WHEAT (Triticum aestivum L.)
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Date
2023
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RPCAU, Pusa
Abstract
In the context of global climate change, the influence of environmental stresses such as heat and drought on agricultural production is a crucial concern. The present study was aimed to quantify effects of Drought stress [DS], heat stress [HS] and combined heat and drought [HS+DS] during heading and grain filling stages on wheat yield and to identify physio-biochemical traits which were strongly associated with improved yield and tolerance of wheat under stressful conditions. Wheat genotypes were treated to individual and combined stress treatments under controlled experimental circumstances, simulating heat and drought conditions. To investigate the interactive impact of these stresses on wheat plants, physiological, biochemical, and morphological characteristics were evaluated. Independent and combined drought and heat stress negatively affect wheat yield and physiology. Five promising wheat genotypes were exposed to [HS], [DS] and [HS+DS] treatments after heading stage. Sowing was done on 28th November, 2022. Grain yield was reduced by 31.9%, 61.6% and 66.6% under HS, DS and HS+DS respectively. There was significant (P<0.05 to <0.01) genetic diversity observed for traits across the genotypes. Major traits that contribute to the yield loss under HS, DS and HS+DS was grain yield, seed set and total biomass. On the other hand traits such as SPAD, relative water content and transpiration rate were positively correlated with yield and biomass. Under heat stress, wheat plants exhibited reduced photosynthetic efficiency, altered antioxidant enzyme activity, and changes in hormonal regulation. Drought stress led to decreased water potential, stomatal closure, and accumulation of ROS species. Grain yield is reduced due to reducing metabolism and mobilization of reserves to developing grains and leaves. A significant variations was observed in the combination of HS and DS where all the traits measured showed higher variations than the individual HS and DS. More over genotypes under HS showed more grain yield and helps to maintain more biomass. During individual and combined stress we have seen accumulation of more ROS species which causes damage to the plant system. Genotypes having a major contribution under different stress treatments may lead to improved varieties with heat and drought tolerance. To best of over knowledge, the present study which used physiological and biochemical traits to explain the variation in grain yield and related traits in wheat genotypes. This study also aimed to find the root morphology under combination of heat and drought stress. The findings show complex alterations in root morphology and architecture as a result of combined heat and drought stress. Combination of both stress resulted in a reduction in root growth characteristics such as volume, area, and length. Root volume, area and length was reduced by 42.8%, 27.8% and 32% respectively when compared to control.