The combined effects of gibberellic acid and salinity on some antioxidant enzyme activities, plant growth parameters and nutritional status in maize plants

Abstract

The combined effects of salt stress and gibberellic acid (GA3) on plant growth and nutritional status of maize (Zea mays L. cv., DK 647 F1) were studied in a pot experiment. Treatments were (1) control (C): nutrient solution alone, (2) salt stress (S): 100 mM NaCl, (3) S + GA1: 100 mM NaCl and 50 ppm GA3 and (4) S + GA2: 100 mM NaCl and 100 ppm GA3. Salt stress (S) was found to reduce the total dry matter, chlorophyll content, relative water content (RWC), but to increase proline accumulation, superoxide dismutase (SOD; EC 1.15.1.1), peroxidase (POD; EC 1.11.1.7) and polyphenol oxidase (PPO; 1.10.3.1) enzyme activities and electrolyte leakage. GA3 treatments overcame to variable extents the adverse effects of NaCl stress on the above physiological parameters. GA3 treatments reduced the activities of enzyme in the salt-stressed plants. Salt stress reduced some macro and micronutrient concentrations but exogenous application of GA3 increased these to levels of control treatment. Foliar application of GA3 counteracted some of the adverse effects of NaCl salinity with the accumulation of proline which maintained membrane permeability and increased macro and micronutrient levels.