Differential responses of leguminous tree species to drought stress: implications for agroforestry and restoration in arid and semi-arid climates

Drought stress significantly affects tree growth, physiology, and biochemical responses, influencing species selection for agroforestry in arid and semi-arid regions. This study evaluated the drought tolerance of four leguminous tree species (Albizia lebbeck, Dalbergia sissoo, Prosopis cineraria and Vachellia nilotica) under five drought stress treatments (T1 = 70%, T2 = 60%, T3 = 50%, T4 = 40%, T5 = 30% field capacity) for one year. Growth parameters, physiological traits and biochemical responses were observed. Data were analyzed using randomized complete block design with factorial arrangements. Results of the data analysis showed significant reductions (p < 0.05) in shoot length, biomass, and chlorophyll content under severe drought (T5). Among the species, P. cineraria exhibited the highest drought tolerance, maintaining higher proline (8.22 mg g(-)(1)) and phenolics (301.73 mg g(-)(1)) levels, indicating strong osmotic and antioxidant responses. D. sissoo exhibited moderate resilience, while A. lebbeck and V. nilotica showed significant growth reductions under severe drought. Root biomass increased with drought stress, particularly in V. nilotica, suggesting an adaptive mechanism for water acquisition. Enzymatic antioxidant activities (SOD, CAT, POD) increased significantly in response to drought, particularly in A. lebbeck. These physiological and biochemical responses show that P. cineraria is the most drought-resistant species, recommended for restoration. At the same time, A. lebbeck, V. nilotica and D. sissoo are recommended for agroforestry in arid/semi-arid environments due to their growth potential under moderate drought conditions. These findings provide valuable insights for species selection in sustainable agroforestry and ecological restoration under increasing water scarcity.