Elucidating stress responses in Prunus rootstocks through comprehensive evaluation under drought, heat shock and combined stress conditions

• Significant variations in stress tolerance observed among rootstocks. • Combined drought and heat stress caused more severe effects than individual stressors. • Stress conditions led to substantial increases in proline accumulation and antioxidant enzyme activities. • GF 677 rootstock showed notable ABA accumulation under combined stress. • Rootpac 40 and Marianna 2624 consistently demonstrated superior tolerance across stress treatments. Abiotic stresses, particularly drought and heat, pose significant threats to agricultural productivity and global food security. This study, therefore, investigated the responses of seven Prunus rootstocks (Garnem, GF 677, Marianna 2624, Myrobolan 29C, Rootpac 20, Rootpac 40, and Rootpac R) to drought, heat shock, and their combination, as well as their recovery potential. The present research encompassed a comprehensive analysis of some morphological, physiological, and biochemical parameters under controlled conditions. Our results revealed significant rootstock variations in stress tolerance and recovery potential. Rootpac 40 and Marianna 2624 consistently demonstrated superior tolerance across stress treatments, maintaining up to 30% higher relative shoot length and 25% higher stomatal conductance compared to other rootstocks under combined stress. Conversely, Rootpac 20 displayed heightened sensitivity, exhibiting up to 40% reduction in chlorophyll content and 50% increase in H 2 O 2 levels under combined stress. GF 677 showed notable ABA accumulation, with a 6.9-fold increase under combined stress compared to control conditions. The combined drought and heat stress treatment induced significantly more severe impacts than individual stressors across all rootstocks. Proline accumulation increased by up to 9.3-fold under combined stress compared to 3–4 fold increases under individual stressors. Antioxidant enzyme activities were significantly upregulated under stress conditions, with Garnem, Rootpac 40, Rootpac R, and Marianna 2624 showing 3.6 to 5.1-fold increases under combined stress, depending on the specific enzyme. This comprehensive evaluation provided valuable insights into rootstock-specific stress response mechanisms and recovery potentials, offering a foundation for informed rootstock selection and breeding strategies aimed at enhancing stone fruit resilience under changing climatic conditions.