Determination of irrigation set points for cranberries from soil-and plant-based measurements

Abstract

Cranberry production requires accurate irrigation management to optimize crop yield and reduce water use. However, irrigation guidelines for that crop are scarce and empirical. The objective of this study was to identify appropriate soil matric potential (ψ) irrigation set points for cranberry production. A three-step process was used to evaluate the set points. Crop water requirements were first evaluated in the field and, second, combined to soil physical properties with a hydrological model to estimate irrigation set points. Third, experimental measurements were carried out in a growth cabinet and in the field to validate the set point estimates from independent observations. Irrigation set point estimates obtained from yield response curves, photosynthesis and transpiration measurements, and soil physical properties were all consistent and suggest that soil matric potential be maintained between −4.0 and −7.0 kPa to ensure an adequate water supply to the crop and optimal fruit yield. Yield responses suggest that cranberries are highly sensitive to small changes in soil matric potential, showing differences of about 20 000 kg ha−1 when outside of the −4.0 to −7.0 range, with a maximum yield between 35 000 and 40 000 kg ha−1, depending on the site.