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GROWTH MODULATION AND ION PARTITIONING IN SALT STRESSED SORGHUM (SORGHUM BICOLOR L.) BY EXOGENOUS SUPPLY OF SALICYLIC ACID

TAHIR MAHMOOD¹, NAEEM IQBAL^{1 *}, HAMMAD RAZA¹, MUHAMMAD QASIM¹ AND M. YASIN ASHRAF²

Abstract: An experiment was conducted to investigate the possible involvement of exogenous salicylic acid in salinity tolerance of two sorghum (Sorghum bicolor L.) lines, viz., PARI-S-4 and YSS-9. Three salinity levels i.e., 0, 60 and 120 mmol NaCl were developed at the time of seed sowing. Foliar spray of salicylic acid (0, 25 and 50 mg L^-1) was applied 14 days after germination. Increasing salinity treatments reduced the fresh and dry mass of both root and shoot. Plants treated with salicylic acid showed no recovery from salt induced reduction in biomass production. Root/shoot fresh and dry mass ratio, however, was not affected by salinity and salicylic acid treatments. Salicylic acid treated plants showed no recovery from excessive accumulation of Na⁺ in their shoot/root, when under salt stress. Reduction in the accumulation of K⁺ in salt treated plants not compensated by exogenous application of salicylic acid. Salt stressed plants treated with salicylic acid, however, showed higher shoot Ca²⁺ than untreated ones. Exogenous application of 25 ppm of salicylic acid proved to be more effective in reducing the salt induced perturbance in shoot Ca²⁺ as compared to salicylic acid level of 50 mg L^-1. Shoot and root Na⁺/ K⁺ ratio though increased with increase in salinity levels, which was not reversed by exogenous supply of salicylic acid.

¹Plant Physiology Lab, Department of Botany, GC University, Faisalabad, Pakistan

² Stress Physiology Lab., Nuclear Institute of Agriculture and Biology (NIAB), Faisalabad, Pakistan