ROLE OF PHYTOHORMONES IN MITIGATING WATERLOGGING STRESS IN SOYBEAN

Abstract

Waterlogging is a devastating environmental stress for soybean. A pot experiment was conducted at Department of Agronomy, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during kharif-II season from August to November, 2019 to find out the time-dependent responses of morpho-physiological, anatomical and biochemical attributes of soybean (Glycine max) to waterlogging stress and the role of foliar application of phytohormones in mitigating the adverse effects of waterlogging condition. The experiment was conducted following completely randomized design (CRD) with three replications consisted of 12 treatments as T 1 : control, T : 0.5 mM salicylic acid (SA), T 3 : 0.1 mM kinetin (KN), T 4 2 : waterlogged for 3 days, T : waterlogged for 3 days + 0.5 mM SA, T waterlogged for 6 days, T for 6 days + 0.1 mM KN, T 8 6 : waterlogged for 3 days + 0.1 mM KN, T : waterlogged for 6 days + 0.5 mM SA , T 10 : waterlogged for 9 days, T : waterlogged for 9 days + 0.5 mM SA, T 12 11 : waterlogged for 9 days + 0.1 mM KN. Plants waterlogged for 3 days showed fewer damaging effects than 6 and 9 days of waterlogging. Leaf number, branch number, shoot length, root length, fresh weight and dry weight of 3 days waterlogged plants were higher than 6 and 9 days of waterlogging. Due to the exogenous application of SA and KN, the number of leaves, the number of branches, shoot length, root length, adventitious root were significantly increased. The number of pods per plant, seed yield and 1000-seed weight were higher due to exogenous application of salicylic acid and kinetin than waterlogging condition. Proline (Pro), malondealdehyde (MDA), H 2 O and electrolyte leakage (EL) increased under the waterlogging condition, which indicates higher oxidative stress. However, exogenous application of SA and KN significantly enhanced plant morpho-physiological and anatomical features and decreased Pro, MDA, H 2 2 O content than the waterlogged plants without phytohormone supplementation. Thus, the study indicates that the foliar spray of SA and KN is an effective approach in improving the growth and reproductive stage against waterlogged conditions.