EFFECT OF SILICON ON GERMINATION, GROWTH, PHYSIOLOGY, YIELD AND ANTIOXIDANT DEFENSE OF WHEAT UNDER SALINE CONDITION

Abstract

A pot experiment was conducted at the experimental shed of the Department of Agronomy, Sher-e-Bangla Agricultural University, Bangladesh during winter season (2013-2014) with a view to find out the regulatory roles of exogenous silicon (Si) in growth, physiology, yield and antioxidant defense systems of wheat under different salt stress condition. The experiment was carried out with two varieties i.e. BARI Gom 21 and BARI Gom 25 and 10 other treatments viz. control (without salt), Si (1 mM Nasilicate),

S50 (50 mM NaCl), S50+Si (50 mM NaCl with 1 mM Si), S100 (100 mM NaCl), S100+Si (100 mM NaCl with 1 mM Si), S150 (150 mM NaCl), S150+Si (150 mM NaCl with 1 mM Si), S200 (200 mM NaCl) and S200+Si (200 mM NaCl with 1 mM Si). Seed germination percentage, number of normal seedling, length of shoot and root, fresh weight of shoot and root and dry weight were decreased under the stress condition but the number of abnormal seedling increased. Salt stresses significantly reduced the plant height, tiller hill -1 , fresh weight and dry weight of both varieties at all growth duration. Leaf relative water content (RWC) and chlorophyll (chl) content also reduced due to salt stress. The malondialdelyde (MDA) and H 2 O were increased under the stress condition. The ascorbate (AsA) content, reduced glutathione (GSH) and GSH/GSSG ratio were reduced by salt stresses (50, 100, 150 and 200 mM NaCl respectively). But the glutathione disulfide (GSSG) amount increased with an increase in the all level of salinity. The ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and catalase (CAT) activities showed a significant reduction in response to salt stress but CAT increased only at 100 mM NaCl. The glutathione S-transferase (GST) and glutathione reductase (GR) activity increased significantly with severe salt stress (S200). But the activity of peroxidase (POD) was decreased with increasing salinity level. At harvest, salt stresses reduced the effective tiller hill -1 2 , 1000 grain weight, grain yield, straw yield and harvest index for both of varieties. However, number of non-effective tillers hill -1 significantly increased in response of salt stress. Exogenous Si application with salt stress improved germination, crop growth parameters, physiological parameters, reduced oxidative damage and yield in both cultivars where BARI Gom 25 showed better tolerance. But, Si application could not improve germination, crop growth parameters, physiological parameters and yield at extreme level of salt stress (S200).