GROWTH AND MINERAL ACCUMULATION OF APPLE TREES

Trees were spaced 2.5 x 4 m and drip irrigated twice a week. Fertilizers (150 kg N and 300 kg KCl ha^-1) were applied through the irrigation system at regular intervals throughout the growing season. At the end of each growing season, prior to leaf abscission, two average size trees were cut off at soil level, divided into leaves, current extension and older growth. The third year trees carried an average of 6.75 kg fruit, a representative sample of which was analysed. Tree parts were washed, dried, ground and thoroughly mixed before mineral analysis.

The total annual shoot growth of the Jonathan trees was 16, 105 and 88 m for the first three years of growth. Total dry weight at the end of the second and third year was 4.85 and 10.58 kg/tree.

Total nitrogen and potassium contents at the end of the second year of growth was 33.2 and 22.0 g/tree and at the end of the third year 54.4 and 48.2 g/tree respectively.

Fruit analysis showed that the amount of nitrogen and potassium removed was 0.46 and 1.58 kg t^-1 fruit, respectively.

Calculation of the minerals removed per unit area (Table 44.1) indicates that fertilizer requirement of an apple orchard is low compared to other, annual crops.

Table 44.1 MINERAL (g/tree) AND DRY WEIGHT (DW) (kg/tree) CONTENT OF APPLE TREES