WOOD AND TREE AGE AS FACTORS INFLUENCING THE ABILITY OF APPLE FLOWERSTO SET FRUIT

The different fruit setting ability of flowers borne on different aged wood and trees of 'Cox's Orange Pippin' apple was examined. Developme ntal and physiological changes of flower buds were examined from bud b urst to full bloom and related to their ability to set fruit. The capa city of apple flowers on young wood to set fruit was considerably less than that on older wood and although fewer fruits were retained until final set, it was the lack of initial set that limited cropping. Ther e were gross morphological differences between flowers on different ag ed wood. Flower clusters on young wood typically had smaller leaf area s and mean flower weights as well as fewer flowers than those on older wood. The reduction in flower cluster size did not appear to be the o bvious result of competition between reproductive and vegetative growt h for mineral nutrients. Female fertility, effective pollination perio d. and the microscopical anatomy of flowers were also examined. Flower s on both young wood and trees showed reductions in the effective poll ination period and ovule condition. Directly after pollination the pro portion of degenerate ovules was shown to decline significantly, indic ating that the egg-sacs were beyond fertilization.