PREHARVEST AND STORAGE QUALITY OF BRAEBURN APPLE FRUIT GROWN UNDER WATER-DEFICIT CONDITIONS

Six-year-old 'Braeburn' apple trees (Malus domestica Borkh.) on MM106 rootstock were studied to determine the influence of withholding irrig ation on fruit composition both before harvest and during storage. Tre es were either fully irrigated (I) according to commercial practice, o r not irrigated (NI). Rainfall was excluded from the rootzone of all N I trees and three of the six I trees from 105 days after full bloom (D AFB). The NI trees had lower leaf water potential (Psi) than I trees f rom 110 DAFB. Fruit were sampled at 2-week intervals from 130 DAFB unt il 192 DAFB. Some fruit picked at 192 DAFB were placed in cold storage for 12 weeks at 0 degrees C. Fruit were analysed at 3-week intervals until 84 days in storage. No difference in fruit weight or crop load w as observed between treatments. Before the final harvest, NI fruit had higher concentrations of total soluble solids (TSS), titratable acidi ty (TA), sucrose, sorbitol, and total soluble sugars, and a lesser con centration of nitrogen than I fruit. Soluble sugar levels increased du ring storage for I and NI fruit. However, larger increases in the conc entrations of fructose, sucrose, and total soluble sugars occurred in the NI compared to I fruit. No difference in the concentration of Ca, Mg, K, and P was observed between treatments. The observed differences in composition preharvest and during storage of the I and NI fruit in dicate an improvement of some attributes in NI fruit.