Exogenous application of Salicylic Acid alleviates drought stress of rubber nursery plants in the Intermediate Zone of Sri Lanka

Drought is considered as one of the main environmental threats for plants that limits the growth and development. In the present study, salicylic acid (SA) was applied to mitigate the drought stress of rubber nursery plants. The study was conducted at Monaragala Sub Station, Rubber Research Institute of Sri Lanka during the dry months from May to September in 2015. The experimental design was Randomized Completed Block Design (RCBD) with five replicates. Treatments were drought-stressed (withholding of water), three concentrations of SA (0.1mM, 0.3mM and 0.5mM) and control(C) kept under regular irrigation. Drought was imposed by withholding water by weekly and lifesaving irrigation was done throughout the nursery period. Measurements were taken on morphological and physiological characters of seedling plants.

 

Plants which were treated with SA as a soil drench at 0.1 mM, 0.3 and 0.5mM concentrations showed significant difference on drought stress plants when compare the stressed plant. Chlorophyll content and stomatal conductance (gs) in seedlings reduced drastically under moisture stressed conditions. Dry matter accumulation also decreased in drought stressed plants as compared to those treated with SA at 0.3 and 0.5mM concentrations. This indicates that the application of SA had a positive effect on stomatal conductance and biomass accumulation under water stressed conditions.

 

In conclusion, the drought-stress decreased the growth of rubber nursery plants to a greater extent and exogenous application of SA at 0.3 mM and 0.5 mM concentrations found to be effective in alleviating drought stress under sub optimal conditions in the Intermediate zone in Sri Lanka.