ROLE OF TRACE ELEMENTS IN MITIGATING SALT STRESS OF SOYBEAN

Abstract

Like other abiotic stresses, salinity adversely affects the vital morphological, physiological and biochemical mechanisms of plants and ultimately leads to yield reduction worldwide. This experiment was carried out to study the morphological, physiological, biochemical, phenotypical and anatomical responses of soybean (Glycine max L. cv. BINA Soybean-5) upon exposure to different levels of salinity and to investigate the role of exogenous application of selenium (Se) and boron (B) in mitigating salt stress. Plants were treated with 0, 150, 300 and 450 mM NaCl at 20 and 35 DAS. Exogenous application of Se (0.50 µM Na 2 SeO 4 ) and B (1 mM H ) was done individually (Se, B) and combinedly (Se+B) at 20 DAS and continued at three days interval until pod filling stage under normal and saline condition. Plants exhibited a reduction in plant height, root fresh weight, root dry weight, shoot fresh weight, shoot dry weight, number of branches plant −1 , leaf area, relative water content and SPAD value under salinity in a dose-dependent manner, which were observed for assessing the growth and physiological responses. However, proline content and oxidative stress indicators such as MDA content and H 2 O content were increased with the increase of salinity. Consequently, it caused a reduction in number of flowers plant −1 , pod length, pods plant −1 , seeds pod −1 2 , seed yield plant −1 , stover yield and biological yield. In responses to 300 and 450 mM NaCl-induced salt stress, plant death occurred after completing the vegetative stage. Phenotypical and anatomical parameters showed a visible deleterious effect of different levels of salinity on growth and number of stomata, respectively. On the contrary, exogenous application of Se, B and Se+B reverted the negative effect of salinity. The combined application of Se+B showed a slight difference in result than Se or B alone. The findings indicated that exogenous application of Se, B and Se+B mitigated the adverse effects of salinity by upregulating physiological and biochemical processes and by enhancing growth parameters.