Postharvest deficit irrigation in ‘Tatura 204’ peach: Subsequent productivity and water saving

Variable and unreliable water supply due to drought substantially reduced irrigation allocation to Australian peach growers from 2005 to 2009. Strategies to maintain productivity with less water were a high priority. Reduced irrigation allocation is likely to continue due to drought and diversion of water for environmental flows. The objective of this study was to investigate the effects of postharvest water deficits on subsequent yield and fruit quality. Treatments were imposed immediately after harvest in 2008 (Year 1, Y1), 2009 (Year 2, Y2) and 2010 (Year 3, Y3) in a commercial ‘Tatura 204’ peach (Prunus persica (L.) Batsch) orchard in the Goulburn Valley Region of Victoria, Australia. Irrigation treatments were 50%, 80%, 100%, 150% and 190% of grower postharvest irrigation practice. In all years the average postharvest midday leaf water potential (ψleaf) increased with irrigation application. After applying the treatments in Y1, in the subsequent season fruit number per lateral prior to thinning was substantially less and even after commercial thinning there was a significant difference (p<0.05) in fruit number per tree at harvest in the deficit treatments. The decrease in fruit number was attributed to flower number per lateral, the duration of flowering and fruit set. There were no differences in subsequent fruit number or yield following the application of the treatments in Y2 and Y3. There was no effect of the deficit irrigation treatments on the subsequent number of defective fruit (split stones, twins, deep sutures or abnormal) in all years. The results showed that 0.9–3.3MLha−1 of water savings can be made by the combination of cutting-back postharvest irrigation to 0.8–1.1MLha−1 and fruit thinning to a defined crop load in ‘Tatura 204’ peach orchards.