ROLE OF SILICON IN MORPHO-PHYSIOLOGICAL, IONIC AND BIOCHEMICAL ACCLIMATI ON OF MUNGBEAN CHALLENGED WITHSALT STRESS

Silicon (Si) is generally considered as a contributing constituent for plant resistance against abiotic stresses. However, the mechanism underlying the role of Si in alleviating salt stress in mung bean (Vigna radiata L) is still poorly understood. Present study deals with response of mung bean to Si application in relation to growth, gas exchange, ionic and antioxidant attributes under saline condition. Two mung bean varieties Azri-2006 and Anmol were grown for four weeks in half strength Hoagland solution. The growth medium was salinized with 03 levels of salinity (control, 35 mM NaCl L-1 & 70 mM NaCl L-1) and one level of Si (1 mM) alone and in combined form by using NaCl and Na(2)SiO(3)salts, respectively. Salinity stress significantly reduced the plant tissue (roots and shoots) biomass, Relative Water Contents (RWC), Membrane Stability Index (MSI), gas exchange attributes and K/Na ratio and increased the plant tissue concentration of malondialdehyde (MDA). Activities of antioxidant enzymes (SOD, POD, APX and GR) of both varieties were reduced due to salt application and this effect was more prominent at high salt level (70 mM NaCl L-1). Addition of Si alleviated salt toxicity is more conspicuous in ANMOL relative to Azri-2006as demonstrated by increasing RWC, MSI, K/Na ratio and activities of SOD, POD, APX and GR. However, the activity of CAT remains unchanged due to Si application under both saline and non-saline condition in both varieties. Our results depicts that Si-mediated alleviation of salt stress is due to enhancement in RWC and photosynthetic capacity, maintaining ions homeostasis and most importantly the increased concentration of antioxidant enzymes SOD, POD, APX and GR in plant tissues.