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

Area of Science:

• Horticulture
• Agricultural Science
• Climate Change Adaptation

Background:

• Global climate change is increasing the frequency and severity of heatwaves in avocado-growing regions.
• High temperatures during early fruit development are a major limiting factor for avocado productivity.
• Hass avocados are particularly vulnerable to heat stress during the fruitlet phenological stage.

Purpose of the Study:

• To evaluate the effectiveness of evaporative cooling systems (pulsing sprinklers or sprayers) in mitigating heatwave damage in Hass avocados.
• To assess the impact of cooling treatments on fruitlet temperature, physiological responses, and overall orchard productivity.
• To compare the efficacy of sprinklers versus sprayers for evaporative cooling in avocado orchards.

Main Methods:

• Over three consecutive seasons, pulsing sprinklers and sprayers were operated above the canopy during spring heatwaves in a Hass avocado orchard.
• Foliage and fruitlet temperatures were monitored using remote and proximal sensing.
• Key physiological parameters including stem water potential and stomatal conductance were measured.
• Leaf salt accumulation and overall orchard productivity (yield) were quantified for treatment and control plots.

Main Results:

• The evaporative cooling system reduced foliage temperature by 6-8 °C and fruitlet temperature by 5-10 °C compared to uncooled trees.
• Stem water potential increased by 0.8-2.0 MPa in the cooled plots, indicating improved plant hydration.
• Average yield increased by 42% over the three years in the treatment plots compared to the control.
• No significant differences in effectiveness were observed between sprinklers and sprayers.

Conclusions:

• Evaporative cooling systems are highly effective in mitigating heatwave damage to Hass avocados.
• Implementing overhead sprinklers or sprayers can significantly improve avocado productivity under heat stress conditions.
• This technology presents a viable strategy for adapting avocado cultivation to the challenges of climate change.