EFFECTS OF SURFACE SOIL PH ON SOIL CATION CONTENT, LEAF NUTRIENT LEVELS AND QUALITY OF APPLES IN BRITISH COLUMBIA

Abstract

’Starkrimson’ Delicious (Malus domestica Borkh.), 10–15 yr old, on seedling rootstock, were sampled in several orchards, selected for uniformly low soil pH (< 5.0), medium pH and high pH (6.5–7.3). Harrold Red Delicious, 20–25 yr old, were sampled in 18 orchards which had low, medium and high pH within each. Soils with low pH were generally characterized by higher exchangeable Mn and lower exchangeable Ca. Exchangeable soil Mg and K levels were not significantly related to soil pH. On soils of low pH, higher leaf Mn was the main plant nutrient response with both Harrold Red and Starkrimson trees. Significantly decreased leaf Ca was observed on the younger Starkrimson trees at low soil pH. Soil pH had no direct effect on fruit firmness, soluble solids, juice acidity, or flesh Ca, Mg and K contents. Poststorage fruit quality problems were primarily surface scald and were not related to differences in soil pH. Incidence of flesh browning was, however, related to low flesh Ca content.