Optimizing citrus deficit irrigation across diverse contexts to balance yield, fruit quality, and water productivity: A global meta-analysis

Citrus is the largest fruit category globally and holds significant economic value. Scientifically regulated deficit irrigation (DI) serves dual functions of water conservation and quality regulation. The effects of DI on citrus yield, quality and water productivity (WP, the ratio of yield to evapotranspiration (ET)) vary across different application scenarios, necessitating a comprehensive global systematic evaluation. We conducted a meta-analysis of 41 studies with 1804 comparisons under field conditions worldwide to examine the effects of DI in citrus on fruit yield, quality and WP, and to identify context-dependent irrigation patterns that may balance citrus yield, fruit quality, and WP under contrasting production objectives. Across the included comparisons, DI reduced yield, single-fruit weight, and juice content by 10.73%, 9.69%, and 4.88%, respectively, while increasing WP by 22.41%, soluble solids by 5.04%, and titratable acid by 6.44%. Vitamin C and the solidity-acid ratio were not significantly changed. The bivariate patterns suggested relatively favorable DI responses in loamy and clayey soils and under higher soil organic matter conditions. When maintaining yield and improving internal fruit quality are prioritized, low-intensity DI and deficits imposed during fruit maturation each showed relatively favorable response patterns. When water conservation and WP are prioritized, low-intensity DI and deficits imposed during stages I–II each showed relatively favorable yield–WP patterns. These findings reveal how deficit intensity, phenological timing, and orchard context jointly shape the trade-offs among citrus yield, fruit quality, and WP, thereby providing an evidence base for the context-specific design and local evaluation of citrus DI strategies and contributing to a broader understanding of citrus responses to DI.