Abstract

Drought stress is a significant challenge for growth of plants and agricultural productivity, impacting global food security. Strigolactones (SLs) are a class of plant hormones recognized for enhancing tolerance to various abiotic stresses; however, their specific function in mitigating drought stress in Eruca sativa (rocket) plant remains unclear. This work investigated the effect of various levels of the synthetic SL analogue GR24 (0, 3 µM, 5 µM and 7 µM) on two rocket plant accessions (Eruca-34961 and Eruca-34936) exposed to drought stress (50% water holding capacity) for four weeks. Drought stress negatively affected growth (45%), chlorophyll content (35%), gas exchange parameters (32%) and relative water content (37%-RWC), while increasing reactive oxygen species (30%-ROS), lipid peroxidation (23%-MDA) and membrane permeability (22%). The application of GR24 mitigated these effects by improving chlorophyll content (64%), photosynthetic efficiency (23%), water status (89%) and accumulation of osmolytes (113%). GR24 also increased levels of proline (8%), phenolics (27%), flavonoids (67%), and ascorbic acid (27%), especially in Eruca-34961, and improved the antioxidant enzyme activities (51%) for ROS detoxification. The optimal level for improving drought tolerance was found to be 5 µM GR24. These results suggest that applying GR24 as a foliar spray may serve as an active strategy to enhance the drought tolerance in rocket plants (Eruca sariva) and promote sustainable agricultural practices in regions facing water scarcity.