Effects of different irrigation levels on plant water status, yield, fruit quality, and water productivity in a drip-irrigated blueberry orchard under Mediterranean conditions

Abstract

As blueberries are susceptible to water stress and their future cultivation in semiarid Mediterranean areas will be challenged by drought, irrigation management strategies will be needed to optimize water productivity and maintain sufficient levels of fruit yield and quality. This study aim was to evaluate the effect of different irrigation levels on plant water status, yield, fruit quality, and water productivity in a drip-irrigated rabbiteye blueberry (Vaccinium ashei Reade 'Tifblue') orchard. Four irrigation treatments based on crop evapotranspiration (ETc) were applied to blueberry plants during two consecutive growing seasons (2012/2013 and 2013/2014): 125 (farmers’ irrigation management, T1), 100 (T2), 75 (T3), and 50 (T4) % ETc. During the study, the average values of midday stem water potential (Ψstem) were −0.85, −0.86, −0.97 and −1.11 MPa for the T1, T2, T3, and T4 treatments, respectively. Fruit weight (FW), yield (Y), fruits per plant (FP), soluble solids (SS), and the water stress integral (WSI) were significantly affected by the irrigation treatments. The water productivity (WP), juice pH, and weight/volume ratio were statistically similar among the treatments. The highest values of Y, FP, and FW were observed in the T1 and T2 treatments, while the lowest values were found in the T4 treatment. In addition, the Y, FP, FW and WSI in the T1 and T2 treatments were significantly similar, but the total water application in the T2 treatment was between 20% and 27% lower than that in the T1 treatment. For the T1 and T2 treatments, the values of Y were between 8.8 and 9.4 kg plant −1, and the Ψstem was >−0.85 MPa during the two growing seasons. The interaction between irrigation treatments and growing season was only significant for the FW, with the lowest values observed in the T4 treatment during the 2012/2013 growing season.