Canopy Position and Light Effects on Spur, Leaf, and Fruit Characteristics of ‘Delicious’ Apple

Abstract

Abstract Spur leaf and fruit characteristics at harvest were measured near the central leader at 1, 2, and 3 m above ground on 17-year-old trees of ‘Oregon Spur Delicious’ apple (Malus domestica Borkh.). Percentages of full sunlight at 1 (bottom), 2 (middle), and 3 m (top) positions were 9, 23, and 48, respectively. Vegetative spurs at the top had greater average leaf dry weight, total leaf number, leaf area, leaf dry weight per spur, specific leaf weight (SLW), and bud diameter than spurs at the bottom. Fruiting spurs at the top had greater leaf dry weight, leaf dry weight per spur, SLW, bud diameter, and spur length than spurs at the bottom. Vegetative spurs had greater values than fruiting spurs for all spur traits except leaf number per spur. Fruit weight, size, and soluble solids were greater at the top than at the bottom. Fruit at the bottom had higher firmness and levels of starch, N, P, K, Zn, Ca, Fe, B, and Mg. SLW, leaf dry weight per spur, and average leaf dry weight of vegetative and fruiting spurs were correlated with percentage of full sunlight. Fruit size, weight, soluble solids, starch, and N content also were correlated with percentage of full sunlight. SLW was correlated with fruit size, weight, soluble solids, and starch, and N, P, Mg, Ca, and Fe content.