'Hacıhaliloğlu' apricot under simulated drought: morphological, physiological, biochemical, and flower biology...

Apricot is one of Türkiye's most important horticultural crops, accounting for approximately 21% of global production. The Hacıhaliloğlu cultivar, responsible for 90% of the country's dried apricot exports, is cultivated in Malatya, where declining precipitation due to climate change poses a significant threat to sustainable production. This study, conducted from 2021 to 2023, aimed to evaluate the effects of different drought irrigation regimes on the morpho-physiological and biochemical characteristics of Hacıhaliloğlu apricot trees under water stress. Four-year-old T-budded saplings were grown in pots and subjected to monthly irrigation treatments during the post-harvest period.The results revealed that drought stress significantly inhibited shoot elongation, reduced leaf size and dry matter accumulation, and impaired pistil development. The T₀ treatment (full irrigation) consistently outperformed all other regimes in terms of shoot length, pistil length, specific leaf weight, and relative leaf dry weight. Drought-exposed trees, especially those under rainfall-only or late irrigation conditions (T₁, T₇, T₈), exhibited increased oxidative damage, as indicated by elevated levels of membrane permeability, H₂O₂, MDA, and antioxidant enzyme activities (CAT, POD, SOD). Moreover, leaf water potential and chlorophyll content declined under prolonged stress conditions.These findings emphasize that irrigation during critical developmental stages particularly July and August, when flower bud differentiation and vegetative growth overlaps is vital for preserving productivity and physiological integrity in apricot trees. Strategic water management in arid and semi-arid regions can mitigate the negative effects of drought stress and enhance tree performance even under limited water availability.