Early survival and growth of Haloxylon ammodendron seedlings under irrigation in arid southern Tajikistan

Understanding plant drought responses is crucial for effective afforestation in drylands. This study aimed to investigate the effects of irrigation (31.25 mm seedling^–1 every 45 days) on the early survival and growth of 3-month-old Haloxylon ammodendron seedlings at an afforestation site established in Tajikistan in 2021. In July 2022 and June 2023, surveys were conducted to compare seedling survival rates, height, root collar diameter (RCD), stem volume per unit area, and height-to-RCD ratio between irrigation (IR) and nonirrigation (NIR) treatments. The IR treatment increased survival rates in 2022 but not in 2023. By 2023, the IR treatment had increased the height, RCD, and stem volume per unit area by 152.9%, 211.2%, and 466.7%, respectively. Between 2022 and 2023, the height, RCD, and stem volume per unit area under IR treatment increased by 112.3%, 310.0%, and 457.1%, respectively, with RCD increments exceeding height increments. These results suggest that the IR treatment promoted biomass accumulation in seedlings, which may have improved the chances of survival under windy conditions by prioritizing RCD increments. This study enhances our comprehension of drought responses in H. ammodendron and contributes to the development of afforestation strategies in diverse arid ecosystems.