Evaluating Overhead Sprinklers and Sprayers for Heatwave Protection in Avocado Orchards.

With global climate change, heatwaves have become more frequent and severe in avocado-growing regions. High temperatures combined with wind and low humidity are problematic for avocados, especially during the early developmental stage of the young fruitlets. Hence, heatwaves during this phenological stage are considered a major limiting factor for avocado productivity. This study evaluated the effects of operating pulsing sprinklers or sprayers installed above the canopy during spring heatwaves over three consecutive seasons in a Hass avocado orchard. We evaluated foliage and fruitlet temperature (using remote and proximal sensing), stem water potential, stomatal conductance, salt accumulation on the leaves, and productivity. The cooling system reduced the foliage temperature by 6-8 °C and fruitlet temperature by 5-10 °C with respect to uncooled trees. Stem water potential was increased by 0.8-2.0 MPa in the treatment plots compared to the control. The cooling treatments led to an average 42% yield increase over the next 3 years. No significant differences were found between the sprinklers and sprayer for any of the measured parameters. Results indicate the effectiveness of an evaporative cooling system for mitigating heatwave damage and improving avocado productivity.