Effects of Ground Cover Treatments on Growth and Photosynthesis in Young ‘Enterprise’ Apple Trees

Abstract

Ground cover mulches were applied annually during the first three years from planting to ‘Enterprise’ apple ( Malus× domesticaBorkh.) trees on M.26 rootstocks. The ground cover treatments were: 1) green compost (GC), 2) wood chips (WC), 3) shredded paper (SP), and 4) mow-and-blow (MB). GC- and WC-treated mulches supplied greater amounts of total N, P, and K to the soil than the SP and MB mulches. GC plots had the highest soil pH, electrical conductivity, [P], and [K] in both years 2 and 3, except for soil pH at 10 to 30 cm depth in year 2. GC- and WC-treated trees had lower specific leaf areas and greater leaf N and shoot growth in year 2 as well as greater trunk cross sectional areas in years 2 and 3. SP trees had the lowest CO ₂assimilation and leaf chlorophyll concentration (SPAD) in year 2. GC and WC treatments would be suitable ground cover mulches from the aspect of tree growth, CO ₂assimilation, and reproductive capacity in establishing an organic orchard in the Southern USA apple growing region.