Effects of nitrogen and potassium fertilization on the growth, yield and pitburn of apricot (cv. Bergeron)

Nitrogen (N) and potassium (K) fertilization were studied in apricot trees. Increasing N enhanced vegetative growth, yield and average fruit weight, but reduced fruit colouring. More effect was seen by increasing N from 0 to 25 kg ha(-1) than by increasing from 25 to 150 kg ha(-1) K fertilization did not affect vegetative growth or yield but tended to stimulate fruit colouring and enhance soluble solids concentration of fruits. N and K interacted to affect vegetative growth and pitburn. Pitburn increased significantly as N was increased from 25 to 150 kg ha(-1). Concurrently, fruit N content increased and Ca content decreased suggesting that these nutrient concentrations are related to pitburn incidence. Of the levels of N studied, 25 kg ha(-1) was the most commercially suitable, since yields were only slightly less than at 150 kg ha(-1) but pitburn was significantly lower.