Abstract
BACKGROUND: Drought and heat stress are significant concerns to food security in arid and semi-arid regions, where global warming is predicted to increase both frequency and severity. To cope with these challenges, the use of drought-tolerant plants or technological interventions are essential. In this study, the effects of foliar potassium nitrate (KNO(3)) application on the stress tolerance and recovery of Myrobalan 29C rootstocks (Prunus cerasifera Ehrh.) were evaluated. These rootstocks are widely recognized for their adaptability and are extensively used in fruit production. To assess their response, the rootstocks were subjected to drought, heat shock, or a combination of both stressors. Additionally, they were treated with 1.0% KNO(3) via foliar application. Throughout the stress and recovery periods, various morphological, physiological, and bio-chemical parameters were measured. RESULTS: Based on our results, KNO(3) treatment improved LRWC, Chl stability, SC, and key stress markers like proline, MDA, H(2)O(2), along with antioxidant enzymes CAT, SOD, POD during both stress and recovery phases. Moreover, our results emphasized KNO(3)'s critical role in hormone regulation under stress. KNO(3) application significantly altered hormone levels, notably increasing ABA during drought and heat shock stress, essential for stress response and adaptation. In contrast, IAA, GA, and cytokinin's significantly increased during the recovery phase in KNO(3)-treated plants, indicating improved growth regulation and stress recovery. In addition, KNO(3) application improved the recovery process of the rootstocks by restoring their physiological and biochemical functions. CONCLUSION: This study suggests that the application of foliar KNO3 is an effective technique for enhancing the drought and heat tolerance as well as the recovery of Myrobalan 29C rootstocks. These results hold significant value for farmers, policymakers, and researchers, as they offer crucial insights into the development of drought-tolerant crops and the management of climate change's adverse effects on agriculture.