The effects of 0, 180 and 360 kg/ha K20 as KCI applied to apples from plantation, followed by 0, 270 and 540 kg/ha to trees in bearing were tested on a heavy (38% clay) soil in the Hula Valley. Yield of Jonathan and Granny Smith was increased by the highest dressing, although non significantly in Granny Smith. There was no yield response in Golden Delicious. There were no effects on trunk growth. In the absence of K, leaf K content declined to 0.9% in bearing trees and potassium fertigation improved this to 1.2 - 1.3%, inducing marginal Mg deficiency which was corrected by two sprays of 1% magnesium nitrate. Applying K widened the K/Ca ratio of fruit peel and flesh but without adverse effect on incidence of bitter pit or other storage disorder. It was concluded that the requirement of apples on this soil is for 540 kg/ha K20 applied by drip irrigation.
The effects of 0, 180 and 360 kg/ha K20 as KCI applied to apples from plantation, followed by 0, 270 and 540 kg/ha to trees in bearing were tested on a heavy (38% clay) soil in the Hula Valley. Yield of Jonathan and Granny Smith was increased by the highest dressing, although non significantly in Granny Smith. There was no yield response in Golden Delicious. There were no effects on trunk growth. In the absence of K, leaf K content declined to 0.9% in bearing trees and potassium fertigation improved this to 1.2 - 1.3%, inducing marginal Mg deficiency which was corrected by two sprays of 1% magnesium nitrate. Applying K widened the K/Ca ratio of fruit peel and flesh but without adverse effect on incidence of bitter pit or other storage disorder. It was concluded that the requirement of apples on this soil is for 540 kg/ha K20 applied by drip irrigation.