Inducing salinity tolerance in red pepper (Capsicum annuum L.) through exogenous application of proline and L-tryptophan

Deterioration of agricultural lands due to salinity is one of the serious threats in irrigated areas of the world. Confronting the influence of salinization in agriculture is a key for achieving food security. Red pepper (Capsicum annuum L.) is not only economically but also nutritionally, important for human diet. A study was conducted to ameliorate the effect of salinity on the production and quality of red pepper by exogenous application of osmolytes. Two potential osmolytes i.e. proline and L- tryptophan were exogenously applied solely and in combination (@ 50 mM and 0.12 mM, respectively). There were three salinity levels i.e. ECe; 0.6, 4.04 and 6.11 dS m-1. Results showed that plant height, root length, plant biomass and yield were significantly decreased, while significant increase in Na+ and Na+/K+ ratio was observed with increasing level of salinity. A significant improvement in growth, yield and quality was observed when both osmolytes were exogenously applied under salinity stress. The combined use of proline and L-tryptophan was more effective for reducing the inhibitory effect of salinity as compared to sole application of these osmolytes. It is concluded that the combined application of proline and L-tryptophan (@ 50 mM and 0.12 mM, respectively) was more effective for improving growth of red pepper under normal conditions as well as salinity stressed conditions.