Annual Dry Matter Production and Partitioning Over the First 5 Years of a Bed System of Crispin/M.27 Apple Trees at Four Spacings

Abstract

(1) The yield, leaf area and dry weight were measured over the first 5 year of Crispin/M.27 apple trees, grown as a bed system at four tree densities from 4444 to 8889 trees ha-1. (2) The trees reached their ceiling yield, leaf area and light interception in their third year after planting, following a small crop of fruit in year 2. The seasonal pattern of leaf area development varied considerably over the first 3 years, with an earlier and larger maximum leaf area being recorded as the trees aged. (3) At the closet spacing the trees intercepted over 80% of photosynthetically active radiation (PAR) from the end of June until October in year 3. These trees had a leaf area index of 3.3, produced 78 t ha-1 fresh weight of fruit, and 17 t ha-1 of dry matter of which 65% was fruit, 23% leaves and 12% woody tissues including roots. Similar values were recorded in years 4 and 5. Cropping markedly reduced root and shoot extension growth. (4) Trees at lower densities had lower yields, leaf areas and light interception, but spacing had no clear effect on the efficiency of energy conversion of intercepted PAR into dry matter, which averaged 3.3% in year 3 and 2.8% in year 4 over all spacings. Equivalent growth efficiencies were 1.9 and 1.6 g MJ-1 of PAR, respectively.