Abscisic acid content and sugar metabolism of peaches grown under water stress

A water stress treatment was imposed on peach trees [Prunus persica (L.) Ba tsch 'Kansuke Hakuto' (Peach Group)] to elucidate the relationship among su gar accumulation, sugar metabolism, and abscisic acid (ABA) in fruit under water stress. Treatment was carried out on peach trees grown in containers from 8 July 1996 [80 days after full bloom (DAFB)] for 16 days, to achieve a predawn water potential of -0.8 to -1.1 MPa compared to that of -0.4 to - 0.6 MPa in control trees. Levels of sorbitol, sucrose, and total sugars, as well as the activity of sorbitol oxidase increased in fruit of water stres sed trees under moderate water stress (-0.8 MPa), whereas under severe wate r stress (-1.1 MPa), no difference between the water-stressed trees and the controls was observed. Water stress also induced an increase in ABA in the fruit. These initial results indicated that water-stress-induced ABA accel erated sugar accumulation in peaches by activating sorbitol metabolism.