Nitrogen fertilization and orchard-floor vegetation management affect growth, nutrition and fruit quality of Gala apple

Gala apple (Malus × domestica Borkh) trees on M.26 rootstock planted in 1989, were subjected to a factorial combination of treatments involving two N fertilizations (N1 and N2) and two orchard-floor vegetation-management treatments (V1 and V2), 1990–1995. Single annual, spring-broadcast application of N at 80 kg ha−1 were made at N1, while N2-treatments involved split N applications of either 2 × 100 kg ha−1 (1990–1993) or 3 × 80 kg ha−1 (1994–1995). Herbicide strips (1.5-m width) were maintained free of orchard-floor vegetation year-round (V1) or annually until mid-July (V2). The high N regime (N2) increased leaf and fruit N concentration and decreased fruit P and leaf and fruit K concentrations but had few negative effects on fruit quality, decreasing harvest fruit ground red color in 2 yr and firmness in a single year and titratable acidity of stored fruit in 2 yr. Increased tree yield was measured at N2 only in 1995. Greater vegetation competition in the V2 treatment decreased yield in 1991–1992 and c...