Different irrigation regimes affect xylem ABA concentrations and the physical berry quality of table grapes at harvest and during postharvest life

A 3-year study examined the effects of deficit irrigation (DI) strategies on some physical quality attributes of 'Crimson Seedless' table grape immediately following harvest, after 28 days of cold storage at 0°C and after an additional shelf life period of 3 days at 15°C. Control vines were irrigated to ensure non-limiting water conditions (110% of crop evapotranspiration), whereas regulated deficit irrigation (RDI) and partial rootzone drying (PRD) treatments received 35% less water during postveraison. The null irrigation treatment (NI) only received natural precipitation (72% less water than the control). Neither total yield nor physical quality at harvest was significantly affected by RDI or PRD. Only the NI treatment, with the worst sensory postharvest scores, reduced berry size. After cold storage, increased berry shattering within the PRD treatment was correlated with the lower ABA at the time of harvest. Neither RDI nor PRD had a significant effect on berry quality at the end of cold storage and retail period. The sensory results were similar in RDI and PRD, both providing grapes that were more acceptable to consumers than the control. Thus, it is possible to decrease irrigation amount by ~30% of table grapes without adversely affecting berry physical quality.