MITIGATION OF SALT STRESS IN SOYBEAN PLANT AT VEGETATIVE STAGE BY EXOGENOUS APPLICATION OF ZINC

Abstract

In this 20 the century, due to global warming, several abiotic stresses (salinity, flooding, drought and metal/ metalloid toxicity) have evolved which drastically effect our environment and life. Among all abiotic stresses, salinity is now-a-days very drastic issue for our agriculture sector and poses a great threat on our food security which is an alarming issue in our world. Micronutrients application have proven to increase tolerance in plants under salt stress. Considering this issue, a pot experiment was carried out on soybean plant (BARI soybean 5) to investigate the salinity induced growth and physiological effect under salinity (5 and 10 dS m −1 NaCl) and the role of exogenous application (priming and foliar application) of zinc in reducing salinity in soybean plant. In this experiment, ZnSO 4 .7H O is used as a protectant against salinity. The experiment was conducted in a completely randomized design (CRD) with three replications consisting of nine treatments T 1 2 : Control, T 2 : Priming with 1 mM ZnSO . 7H 2 O, T 3 : Foliar application of 0.5% ZnSO 4 .7H 2 O, T 4 : 5 dS m −1 salinity, T

salinity + priming with 1 mM ZnSO 4 .7H 2 O , T 6 : 5 dS m −1 salinity + foliar application of 0.5% ZnSO 4 . 7H 2 O, T 7 : 10 dS m −1 salinity, T 8 : 10 dS m −1 salinity + priming with 1 mM ZnSO 4 . 7H 2 O and T 9 : 10 dS m −1 5 salinity + foliar application of 0.5 % ZnSO . 7H O. After germinating seed, treatments were applied on plants in vegetative stage (20 DAS and 30 DAS). All the growth and physiological parameters of soybean plants were negatively affected by both saline conditions at vegetative stage. Zn priming and foliar spray showed the better performance in increasing plant height, root length, fresh and dry weight of root and shoot, chlorophyll content and leaf relative water content in vegetative stage under saline condition, compared to control. Exogenous application of Zn reduced lipid peroxidation (MDA), hydrogen peroxide and proline in saline affected plants, compared to plants under salt stress. This study indicates that Zn is an effective protectant in improving tolerance and increasing the growth and physiology of soybean plants under salt stress.