Regulated Deficit Irrigation of Montmorency Tart Cherry

Regulated deficit irrigation (RDI) has been used in some fruit crops to improve water use efficiency, to control vegetative growth, and to maintain or improve fruit quality.  The effects of RDI on growth, yield and fruit quality of ‘Montmorency’ tart cherry (Prunus cerasus) were studied during the 2007 and 2008 seasons.  Five irrigation treatments were imposed during stage III fruit development on replicated plots in a uniform mature commercial orchard.  Irrigation treatments supplied approximately 30% to 115% of crop evapotranspiration (ET_c) from pit hardening to harvest. Midday stem water potential at harvest was closely correlated with irrigation levels and ranged from 0.8 to 1.2 MPa. Harvested yield did not differ significantly among irrigation levels.  Fruit size differed among treatments and years, but only the lowest irrigation level had significantly more undersized (cull) fruit. Fruit soluble solids content was inversely proportional to irrigation level.  The effects of RDI during stage III fruit development on tree health are not yet clear.  However, RDI treatments in 2007 did not result in noticeable flower doubling, and the severity of visible bark splits resulting from mechanical harvest were inversely correlated with irrigation level.  These results suggest that some level of RDI may improve fruit quality and reduce accumulated trunk injury in ‘Montmorency’ tart cherry.