Hormonal Regulation of Stay Green Trait under Heat stress in Wheat (Triticum aestivum L.)
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Date
2021
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DIVISION OF PLANT PHYSIOLOGY ICAR - INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Abstract
Wheat is one of the most extensively grown cereal crops in the world. Wheat being a winter season crop is often exposed to a short period of heat stress during anthesis and grain filling. Heat stress after anthesis induces leaf senescence and forced maturity results in poor yield. Delaying in leaf senescence after anthesis, is referred as stay-green trait, that maintains photosynthetic activity for a longer period and thus provides higher yield. Therefore, the maintenance of the stay-green trait has prime importance. An alternative approach for maintaining stay green is hormone therapy. Stay green traits have been attributed to higher cytokinin levels and or reduced ethylene production. Therefore, in order to study the hormonal regulation of stay-green trait under heat stress in wheat, the present thesis work was carried out by conducting two experiments. During the first experiment, 32 diverse wheat genotypes were screened for the stay-green trait under dark stress conditions in the lab and two contrasting genotypes were selected for subsequent experiment II. Experiment II was conducted using two contrasting genotypes namely Chirya 3 (stay green type) and HD 2329 (non- stay green type). This experiment comprised of two main treatments i.e. normal sown condition (18 Nov 2020) and late sown (18 Jan 2021) heat stress condition and five sub- treatments for hormonal manipulation i.e. Control (Water spray), Lovastatin (Lova) (an inhibitor of cytokinin), Benzyl aminopurine (BAP), Thidiazouron (TDZ) and Cobalt chloride (CoCl2) (an inhibitor of ethylene) at anthesis stage to alter the endogenous level of phytohormones.
Results of this study revealed the reduction in SPAD value, NDVI, leaf area, MSI, RWC, CTD, photosynthetic pigments, PN, gs, TR, dry matter partitioning, Fv/Fm ratio, YII, yield and its attributes, and enhancement in senescence score, NPQ, lipid peroxidation, H2O2, total soluble sugar, proline content, antioxidant enzymes activity, chlorophyllase enzyme activity under late sown heat stress condition. In general, foliar application of BAP, TDZ, and CoCl2 enhanced SPAD value, NDVI, leaf area, MSI, RWC, CTD, photosynthetic pigments, PN, gs, TR, Fv/Fm ratio, YII, NPQ, total soluble sugar, proline content, dry matter partitioning to ear, yield and its attributes, heat tolerance index and restricted lipid peroxidation, H2O2, chlorophyllase activity, heat susceptibility index while the contrasting results were obtained with the application of lovastatin.
From the present study, it may be concluded that application of BAP, TDZ, and CoCl2 enhanced stay-green trait, heat tolerance, and yield by increasing photosynthetic pigments, PN, gs, TR, partitioning, Fv/Fm, NPQ, YII, osmolytes, MSI, CTD, RWC, antioxidant enzymes activity, leaf area and by decreasing ROS production, Chl degradation, lipid peroxidation, and CHLase activity. Further, lovastatin treatment confirmed the role of cytokinins in the stay-green trait.
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T-10572