ALLEVIATION OF ADVERSE EFFECTS OF WATER DEFICIT STRESS ON WHEAT USING HUMIC ACID

Abstract

To investigate the ameliorative effect of exogenous application of humic acid on wheat (Triticum aestivum L.) under water deficit stress a pot experiment was conducted at the research shade house and laboratory of Crop Physiology and Ecology Department, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during the period of November, 2022 to March, 2023. The experiment was laid out in completely randomized design with three replications. Four growing conditions viz. well water (65% field capacity), water deficit stress (35% field capacity), soil application of humic acid (@ 0.044 g kg-1 soil) under water deficit stress and foliar application of humic acid (@ 200 ppm) under water deficit stress and two wheat varieties (BWMRI Gom 1 and BWMRI Gom 3) were assigned as experimental treatments. Water deficit stress significantly reduced different morphological traits (leaves plant-1, flag leaf length and flag leaf breadth) physiological traits ( relative leaf water content, SPAD value and leaf temperature), biochemical traits ( flag leaf chlorophyll content and flag leaf proline content) and yield traits ( plant height, spikes plant-1, spike length, individual spike weight, spikelets spike-1, grains spike-1, 100 grains weight, grain yield plant-1 and above ground biological yield plant-1) final yield of wheat except proline content of flag leaf of wheat. Exogenous application of humic acid improved these traits at different degrees under water deficit stress. Foliar application of humic acid was found to be more effective to alleviate the adverse effects of water deficit stress on wheat as compared to soil application of humic acid. Soil application of humic acid improved grain yield by 9.13% and 13.86% and biological yield by 9.94% and 5.19% in BWMRI Gom 1 and BWMRI Gom 3, respectively, under water deficit stress condition. Foliar application of humic acid improved grain yield by 24.76% and 25.19% and biological yield by 19.23% and 6.50% in BWMRI Gom 1 and BWMRI Gom 3, respectively under water deficit stress condition. Therefore, it may be concluded that exogenous application of humic acid could alleviate the adverse effects of drought stress on wheat and foliar application of humic acid performed better than the soil application of humic acid.