EFFECT OF SALICYLIC ACID ON GERMINATION, GROWTH, PHYSIOLOGY, YIELD AND ANTIOXIDANT DEFENSE OF WHEAT UNDER SALINITY

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 salicylic acid (SA) in growth, 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 Corn 25 and ten salt stress treatments viz, control (without salt), SA (I mM salicylic acid), S50 (50 mM salt stress), S50+SA (50 mM salt stress with I mM SA). 5100 (100 mM salt stress). S100+SA (100 mM salt stress with 1 mM SA), 5150 (150 mM salt stress), S150+SA (150 mM salt stress with I mM SA). 5200 (200 mM salt stress) and S200+SA (200 mM salt stress with 1 mM SA).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", 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 lI202 were increased under the stress condition. The ascorbate (AsA) content, reduced glutathione (GSH) and GSI-IIGSSG ratio were reduced by salt stresses (50. 100. ISO and 200 mM. 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 (DRAR) and catalase (CAT) activities showed a significant reduction in response to salt stress but CAT increased only at 100 mM stress condition. The glutathione S-transferase (GST) and glutathione reductase (CR) activity increased significantly with severe salt stress (200 mM). But the activity of peroxidase (POD) was decreased with increasing salinity level. At harvest, salt stresses reduced the effective tiller hill". 1000 grain weight, grain yield, straw yield and harvest index for both of varieties. However, number of non-effective tiller hill" significantly increased in response of salt stress. Exogenous I mM SA application with salt stress improved germination, crop growth parameters. physiological parameters, reduced oxidative damage and yield in both eultivars where BARI Gum 25 showed better tolerance. But. SA application could not improve germination, crop groth parameters. physiological parameters and yield at extreme level of salt stress (200 mM).