Effects of postharvest deficit irrigation on sweet cherry (Prunus avium) in five Okanagan Valley, Canada, orchards: II. Phenology, cold hardiness, fruit yield, and quality

Irrigated agriculture in semi-arid regions is expected to increase in the future, which puts greater demands on scarce water resources. Sustainable irrigation strategies in semi-arid regions will support agricultural resilience to climatic change. The response of "Sweetheart"/Mazzard sweet cherry trees (Prunus avium L.) to postharvest deficit irrigation (PDI), as a water con-servation method, was studied over three seasons (2019-2022) in the semi-arid Okanagan Valley of British Columbia, at five commercial orchards. The following irrigation treatments were applied; (i) a control of full irrigation, irrigated according to conventional growers' practice at each orchard, (ii) PDI-30: 27%-33% reduction in irrigation volume, after harvest (67%-73% of control), and (iii) PDI-50: 47%-52% reduction in irrigation volume, after harvest (48-53% of control). Spring phenology (the tim-ing of flower bud development, from side green to full bloom), flower bud moisture content and cold hardiness, and fruit yield and quality (before and after cold storage and shelf-life conditions) were assessed to determine if PDI altered fruit development over the subsequent growing season. Neither PDI-30 nor PDI-50 caused changes in the timing of flower bud phenology, cold hardiness or moisture content relative to the control. PDI treatments also had no effect on fruit yield or fruit quality at harvest or after storage and shelf-life conditions. These results suggest PDI could be used to reduce irrigation water use in semi-arid regions, like the Okanagan Valley, without affecting sweet cherry production or fruit quality.