Irrigation Management Methods to Manipulate Fruit Quality in Blueberry

A trial was initiated in 2004 to compare the effects of sprinkler, microspray, and drip irrigation on water use and production in blueberry.  One of the primary goals was to identify the best irrigation practices for optimizing both yield and fruit quality.  Irrigation was examined in both an early-season cultivar, ‘Duke’, and a late-season cultivar, ‘Elliott’.  Plants were grown on mulched, raised beds and irrigated by overhead sprinklers, microsprays, or drip at 50, 100, and 150% of the crop evapotranspiration requirement (ET_c).  Overall, marketable yield and individual berry weight were higher in plants irrigated by drip than in those irrigated by sprinklers and microsprays.  Yield and berry weight were also higher on average when plants were irrigated at 100% ET_c than at 50% ET_c but were similar between plants irrigated at 100% and 150% ET_c.  Thus, as expected, plants were generally under-irrigated at 50% ET_c and over-irrigated at 150% ET_c; however, this was not always the case.  Yield did not increase between 50% and 100% ET_c when plants were irrigated by drip, and berry weight increased from 100% to 150% ET_c when plants were irrigated by microsprays.  Interestingly, drip reduced berry firmness and soluble solids relative to sprinkler and microspray irrigation, potentially increasing problems with soft fruit during shipping and storage.  Titratable acidity was also lower with drip but only when plants were irrigated at 50% ET_c.  While irrigation method and the amount of water application affected yield and fruit quality in blueberry, more work is needed to identify the best combinations of each to produce the most marketable fruit.