The Effect of Proline Applications on Drought Stress Tolerance in Pepper Seedlings

Proline is an important osmoprotectant that contributes to maintaining osmotic balance and cellular turgor in plants under abiotic stress conditions, while also indirectly regulating the metabolism of reactive oxygen species and increasing stress tolerance. The aim of this study was to determine the effects of foliar application of proline on drought stress tolerance in pepper (Capsicum annuum L.) seedlings during the early developmental stage. In the study, proline was applied foliar spray to pepper seedlings at concentrations of 0, 5, 10, and 15 mM, ensuring that both surfaces of the leaves were completely wetted during application. One day after application, the seedlings were subjected to drought stress for one week without watering. The results showed that proline applications improved growth parameters such as plant height, stem diameter, number and area of leaves, chlorophyll content, relative water content (RWC), and fresh and dry weights of shoots and roots compared to control plants; and also reduced the percentage of damaged tissue and tissue electrical conductivity (EC). The highest efficacy was observed with 10 and 15 mM proline applications. In conclusion, foliar application of proline at concentrations of 10 and 15 mM was found to be a viable method for increasing drought tolerance in pepper seedlings.