Deficit irrigation affects fruit quality, production and resource allocation of ‘d’Anjou’ and ‘Bartlett’ pear trees

Excessive tree vigor is a common problem in North American pear orchards. Strategies like regulated deficit irrigation (RDI) can help manage vegetative growth, improve fruit quality, reduce physiological disorders, and enhance water use efficiency. A two-year study on ‘d’Anjou’ and ‘Bartlett’ pears evaluated their response to three irrigation strategies: (i) full irrigation at 100 % crop evapotranspiration (ETc) throughout the season (CTL), (ii) RDI with 100 % ETc from April–June and 50 % ETc from June–October, and (iii) plant-based irrigation (PBI) similar to RDI but triggered by a stem water potential threshold of −1.25 MPa. Deficit irrigation reduced soil water content, gas exchange, and midday stem water potential. ‘d’Anjou’ pear trees were more vulnerable to water restrictions than ‘Bartlett’. Both RDI and PBI treatments effectively reduced tree vigor and pear psylla damage without compromising yield. In the second year, the number of fruits per tree increased, and water productivity improved by 53 % (RDI) and 40 % (PBI), while water use dropped by 37 % and 28 %, respectively, compared to CTL. Fruits from deficit-irrigated trees were consistently smaller. In a low-crop year, they were sweeter and less firm, suggesting accelerated ripening. RDI reduced fruit size more than PBI, but both treatments improved vigor control and reduced pear psylla damage. In semi-arid regions, plant-based irrigation offers an effective method for managing pear tree vigor, enhancing sustainability, and maintaining desirable fruit quality. • Plant-based irrigation achieved water savings of 28 % and did not decrease yield. • Plant-based irrigation affected fruit size less than ET-based deficit irrigation. • Plant-based irrigation reduced vegetative growth and psylla damage vs. the control. • A −1.25 MPa stem water potential threshold is proposed for summer deficit irrigation. • ‘d’Anjou’ pear trees were more sensitive to water deficit than ‘Bartlett’ trees.