Trees could sustain seasonal drought stress, but their yields will not, to the point of economic unsustainability. Thus, growers must understand the optimal seasonal irrigation requirements and prepare for water shortages. We hypothesized that water deficits would negatively impact the growth of almond trees and the development of their reproductive buds for future years.
To test this, we studied 100 orchards in California between 2020 and 2023. We summarized seasonal irrigation, recorded climate, and measured yields. Additionally, we monitored stress, metabolism, canopy development (satellite data), and transpiration (from satellite and ground calibration). Finally, we constructed large databases, developed a model to predict water consumption in almond orchards, and identified critical periods of drought.
Irrigation up to 600 mm had little effect on almond yields, improved yields between 600–1100 mm, and didn’t affect yields above 1100 mm. Still, the yield functions varied from year to year because rainfall also affected yields. Some orchards transpired according to potential evapotranspiration, while others transpired less. Canopy structure changes explained most of the variability between transpiration and potential evapotranspiration. Additionally, deficit irrigation reduced sugar availability for future growth, decreased canopy area for transpiration, and altered tree responses to irrigation.
We developed a decision-support system and implemented it in an application for California almond growers. The application utilizes geography, historical climate, and real-time satellite imagery. The model ensures optimal utilization of soil-stored rainwater while minimizing the risk of early-season drought stress. The model accounts for water limitations and alerts on emerging drought stress.
