Winter Deployment of Shading Nets Mitigates Frost Injury and Subsequent Yield Loss in a Mature ‘Hass’ Avocado Orchard

Frost damage to reproductive tissues is a major constraint to stable yield in ‘Hass’ avocado (Persea americana Mill.) orchards, yet practical protected-cultivation strategies for mature trees remain limited. While shading nets are widely used to mitigate heat stress, their potential to reduce frost damage in mature, bearing avocado trees remains insufficiently understood. We evaluated the effects of winter deployment of high-density (60%) silver shading nets on microclimate, physiological performance, and productivity of mature ‘Hass’ avocado trees over two consecutive winters. During a severe frost event (minimum −3.5 °C; approximately 11 h below 0 °C), shading nets had little effect on minimum nighttime temperatures but reduced daytime solar irradiance and maximum temperatures. Following the frost event, control trees suffered extensive vegetative and reproductive damage, whereas net-covered trees exhibited substantially lower injury, with floral bud damage declining from 80% to 22%. Net-covered trees exhibited significantly higher maximum quantum efficiency of photosystem II (Fv/Fm; 0.74 vs. 0.48 in control trees). These responses were associated with greater flowering intensity and a significant yield advantage in the subsequent season (16 vs. 0.4 kg tree-¹). In contrast, no treatment differences were observed during a frost-free winter. This findings indicate that winter deployment of shading nets can sustain reproductive performance in mature avocado trees following a severe frost event. Validation across additional orchards and frost events is required to establish their potential as a protected-cultivation strategy to improve orchard resilience under increasing climatic variability.