Relations between tree age, fruit load and mean fruit weight.

Hand fruit thinning was performed for four successive years on 'Gala' apple trees grafted on dwarf P 2 rootstock and planted at a density of 3333 trees/ha. Trees were 5 years old when the experiment started. Three thinning treatments were done with the assumption that apples at harvest should be medium sized (8 fruits per kg), large (7 fruits per kg), or very large (6 fruits per kg). To obtain such results, 84; 74 or 63 fruitlets were left per tree in the beginning of June. Two other treatments included thinning fruitlets with any defects, and no thinning in the control. To avoid subsequent effects of fruit load on blooming intensity, each year new trees were chosen for the experiment. The results indicated that with tree aging fruit load must be decreased to assure the same mean fruit weight.