Abstract

Silicon, after oxygen, is the second most prevalent mineral element on earth’s crust. Plant roots generally take up Si in the form of silicic acid [Si(OH)4], which gets translocated to shoots and then polymerized as silica gel. Exogenous Si fortification induces favourable effects on plant growth and productivity under salt as well as metal stress. Although all plants contain Si, a wide variation in Si accumulation exists between species, where monocots have been reported to take up much more Si than dicots including legumes. Experiments conducted in our lab indicated the potential of AM in enhancing Si uptake, thereby imparting salt and metal tolerance to otherwise low Si accumulating leguminous species. The experimental findings revealed a negative correlation between various agronomic parameters with elevated salt/metal stress. Exogenous Si fortifications along with mycorrhizal inoculations not only reduced the toxic ion uptake and the resultant oxidative burst but also improved plant productivity even under high salt/metal concentrations. In conclusion, investigations highlighted the role of AM in enhancing the benefits of Si nutrition and restoring the rhizobial and mycorrhizal symbioses, thus productivity of grain legumes grown in contaminated soils. In the present talk, I will discuss various mechanisms by which Si and AM mitigates salt and HM stress in two agronomically important legumes species namely Cicer arietinum and Cajanus cajan.