Effectiveness of silicon and rhizoglomus intraradices in imparting nickel tolerance by modulating defense mechanisms in seasonally different legume species

Abstract

In the present study, the relative influence of Si and R. intraradices was evaluated in modulating physiological and biochemical responses of three legume species under Ni toxicity. Ni stress had damaging effects on plant growth, rhizobial and mycorrhizal symbioses, nutrient content and productivity, with impacts being maximum in chickpea, moderate in mungbean and least in pigeonpea. Ni caused oxidative stress that damaged the membrane lipids and proteins. Introduction of Si and R. intraradices, mitigated the toxic effects of Ni stress in all crops. AMF was more beneficial than Si in attenuating deleterious effects, with pigeonpea establishing a stronger AMF symbiosis than other legumes. Si had limited positive benefits, with pigeonpea most responsive towards Si nutrition, followed by mungbean, with least positive effects in chickpea. The ameliorators helped in improving the biomass production, mineral content and rhizobial symbiosis. They also restored the ureide and amide metabolism and mediated their proper transport to other plant parts, leading to better N build up. Moreover, AMF played a vital role in enhancing the glomalin production and boosting the functioning of soil microbial activities. ROS generation ultimately declined and antioxidant functioning was enhanced, thereby lowering the oxidative stress. The combined treatment of Si and AMF further improved all the parameters than their individual treatment, with complete amelioration recorded in pigeonpea and mungbean, whereas no functional complementarity was observed in chickpea. Thus, the bettering of plant physiological parameters could be attributed to higher Si uptake through mycorrhiza and higher mycorrhization due to Si. newline