Antistressful Action of Two Auxin Analogues on Antioxidant Enzymes and Minerals in Tomato (Solanum lycopersicon)

Abstract

Salinity is a worldwide problem for agricultural soils in the production of crops. It reduces yield and limits expansion of agriculture onto previously uncultivated land. Bioregulators play important roles in the growth and development of plants. This study seeks to investigate the effect of two bioregulators, Indole-3- acetic (IAA) and Naphthaleneacetic acid (NAA) on antioxidant enzymes and minerals in the leaves of tomato (Solanum lycopersicon) plants subjected to salinity stress. Seeds of Tropimech and UC 82B tomatoes were soaked in 0, 50 and 150 mg/L of IAA and NAA for 24 hours. The seeds were planted in the screen house in three categories of polythene bags of soil to which 0, 100 and 200mM sodium chloride (NaCl) had been added respectively. After 30 days, the plants were harvested and antioxidant enzyme activity and mineral content determined. The results indicate that there was a significant increase (p<0.05) in the activity of catalase in the tomato genotypes at 100 mg/L concentration of IAA while the 150 mg/L concentration at 200mM NaCl gave significant increase (p<0.05) in peroxidase activity compared to control. Also, 50 mg/L NAA at 100mM NaCl significantly increased (P<0.05) catalase activity relative to control at the different salt levels investigated. The 50 mg/L and 100 mg/L concentrations of IAA gave the highest increase in Cu, Ca and K compared to the control at 0mM of NaCl. The results indicate that IAA and NAA enhanced antioxidant enzyme activity and moderately improved mineral content of tomato under salinity stress. This offers opportunities for adapting to salinity stress and represents improved development of this important vegetable food crop under such conditions.