Effect of assimilate supply on peach fruit maturation and quality

Maturity and sensory evaluation of peach (cv. Suncrest) fruits were evaluated in response to three leaf:fruit ratios, 6, 18 and 30, respectively. Fruit growth rates increased with increasing leaf:fruit ratios so that, at maturity, fruit weights of 75, 140 and 180 g were obtained from the three treatments, respectively. Metabolic activity (oxygen consumption) although indifferent between treatments when fruits were immature, segregated according to leaf:fruit ratios as fruits matured. Autocatalytic production of ethylene was delayed in fruits suffering from nutritional stress and the intensity of ethylene production was also dependent on assimilate supply. Sugars, especially sucrose, accumulated at slower rates when assimilate supply was lowest, i.e. six leaves per fruit. Malic and citric acids metabolisms were influenced by the leaves:fruit ratios. Quinic and shikimic acid levels were reduced according to the treatments.