USING SIMULATION MODELING TO ESTIMATE THE RELATIONSHIP BETWEEN DATE OF FRUIT MATURITY AND YIELD POTENTIAL IN PEACH

Fruit growth data for eight clingstone peach cultivars with dates of f ruit maturity spanning eight weeks, were collected over two years and used with a peach fruit growth and crop yield simulation model to esti mate the effect of date of fruit maturity on crop yield potential. Cul tivars with early dates of fruit maturity were estimated to have subst antially reduced dry weight yield potential compared to later maturing cultivars. However, fruit of earlier maturing cultivars had a higher water content than fruit of late maturing cultivars. These differences in water content offset some of the predicted loss in fruit dry weigh t yield potential related to early fruit maturity, when yields were ca lculated on a fresh weight basis. The estimated sacrifice in fresh cro p yield potential related to advancing fruit maturity beyond the curre nt earliest harvested commercial California clingstone peach cultivars was approximately 1.8 tons ha(-1) day(-1). Within the parameters of t his study, maximum yield potentials for peach are predicted to be achi eved in cultivars maturing during early to mid-August.