Deficit Irrigation in Prunes: Maintaining Productivity with Less Water

Abstract

Prune (Prunus ×domestica L.) trees are believed to be relativelytolerant of water stress, and since the fruit are dried, a low fresh to dryweight ratio (“drying ratio”) of the fruit at harvest will reduce energyrequirements for drying, and improve economic returns to the grower.In previous research we found that, under some orchard conditions,irrigation deprivation was associated with a number of economicallybeneficial effects, including a lower drying ratio of the fruit, andincreased return bloom and final marketable crop yield. Analysis ofthese results was complicated by alternate bearing, and by the fact thattree water stress could differ substantially within the same irrigationregime, depending on soil conditions. After accounting for thesefactors, our analysis indicated that economic yield could be main-tained or increased by managing trees at a moderate level of waterstress. An experiment was established to determine whether middaystem water potential (Ψ