Agronomic management strategies to mitigate almond orchard water stress under drought and irrigation shortages

Abstract

Climate change and reduced water availability increasingly threaten agricultural productivity, especially in Mediterranean regions facing recurrent drought and irrigation restrictions. This study assessed several agronomic strategies to mitigate the effects of extreme drought and limited irrigation on almond trees, as well as their carry-over impacts into the follow ing season. In 2023, six treatments were applied: (i) Rainfed (no irrigation from mid-May); (ii) Control (~1100 m³/ha of water from May to November); (iii) Tree Shaker (Control-level irrigation+mechanical nut thinning); (iv) Disc Pruning (Control-level irrigation+spring canopy reduction); (v) Kaolin (Control-level irrigation+three foliar applications); and (vi) Nut Thinning (Control-level irrigation+manual thinning). Physiological traits, phenology, yield, and evapotranspi ration (via remote sensing) were monitored. Rainfed trees, receiving only 22% of crop water needs and reaching stem water potentials of −4.0 MPa, showed the worst performance: 92% yield loss and 42% tree mortality. Among irrigated treatments, Control and Kaolin had the highest yields in 2023 but declined significantly in 2024 due to carry-over stress effects. In contrast, Disc Pruning showed the greatest improvements in water status throughout the season. Cumulative kernel yield over both years was strongly correlated with integrated stem water potential (R² = 0.87), underscoring the importance of maintaining tree water status. Overall, Disc Pruning and Tree Shaker emerged as promising strategies to sustain almond productivity under extreme drought conditions.