Evaluation of biochemical changes in wheat varieties as influenced by terminal heat stress under varying environments

Abstract

Climate is considered as the major uncontrollable factor in crop production. Alternation in the climate worldwide is predicted to have critical impact on crop production. High temperature negatively affects growth process of wheat by upsetting various physiological and biochemical processes and thereby affecting the nutritional quality of the crop. Heat stress during reproductive growth stages of wheat is detrimental to chloroplast activity, reducing activity of source organs and thereby reducing its sink capacity. Reduction in starch content is the major reason leading to yield loss during heat stress and this is because of accumulation of starch is associated with activities of various enzymes like sucrose synthase, soluble starch synthase, etc which are highly heat labile. Metabolic pathways are most altered during heat stress followed by secondary metabolite biosynthesis pathways. A field experiment was conducted during the Rabi season of 2020-21 at Student’s Instructional Farm of Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya, Uttar Pradesh to evaluate the biochemical changes in wheat varieties as influenced by terminal heat stress. The treatment for the experiment consisted of sowing on three different dates i.e. D1 (30th November), D2 (15th December), D3 (30th December). It was observed that delayed sowing decreased substantially total chlorophyll content, total soluble sugar content in leaves of V1 (PBW-343) and V2 (HD-2967). This reduction was caused due to onset of high temperature during reproductive stage of wheat crop. Variety V3 (Halna) reduced the detrimental effect of heat stress and thus showed greater total chlorophyll content, total soluble sugar content. Proline content in leaves increased with age of crop up to 75 DAS in all the sowing dates this varying dates of sowing because proline is thought to play an adaptive role in mediating osmotic adjustment and protecting sub cellular structure in stressed plants.