EFFECT OF 4 DIFFERENT CANOPY SHAPES ON APPLE YIELDS

The cultivars, Jonathan, Delicious and Granny Smith apple (Malus domes tica Borkh.) trees on MM.106, Northern Spy, Seedling and MM.102 rootst ocks were trained as vase, central leader, palmette and Hawkes Bay mul ti-leader systems for 18 years. Rootstock significantly affected tree size, and there were interactions of rootstock with training systems o r cultivars. There was also an interaction between training systems an d cultivars. In the early years, while the training systems were being established, fruit yield was inversely related to the severity of the pruning; central leader- and palmette-trained trees had higher yields and tree efficiency than Hawkes Bay trees whose yields and tree effic iency were higher than vase trees. When yields reached maximum and the training systems became well established (after about 8 years of crop ping), the total annual yield and tree efficiency per tree of individu al training systems within a cultivar and rootstock differed only slig htly. Cumulative yields of central leader, palmette and Hawkes Bay wer e higher than vase in the early years of all training systems and cult ivars, while tree size was often smaller. In the latter years, cumulat ive yields of the central leader, palmette and Hawkes Bay systems rema ined slightly higher than vase, except with the less vigorous Jonathan and Granny Smith/MM.102 combinations where yields were similar.