Abstract
Water scarcity strongly limits the establishment and productivity of young orchards. Although cover crops are increasingly adopted to improve soil health, their integrated effects on soil-plant-water interactions under drought remain unclear. Here, a two-year field study evaluated Legume, Gramineae, and Legume-Gramineae mixture covers in relation to soil water dynamics, evapotranspiration (ET), and water use efficiency (WUE). Gramineae cover reduced 0-100 cm soil water storage by 5.99% compared with bare soil, whereas the Legume-Gramineae mixture effectively buffered drought-induced water loss. All cover treatments increased total ET, with the mixture showing the highest (10.31%), indicating that enhanced transpiration compensated for reduced soil evaporation. As a result, WUE improved, particularly during winter and spring when water demand was lower. Stepwise analysis identified rainfall as the primary climatic drivers of ET and WUE. Overall, the Legume-Gramineae mixture offers a promising strategy for improving WUE and mitigating drought stress in water-limited orchards.