Effect of tree and branch thinning on growth, yield, and fruit quality of persimmon trees in a high-density orchard

摘要

A study was conducted to evaluate the effect of branch and tree thinning on growth, yield and fruit quality in 8-year-old non-astringent persimmon (Diospyros kaki L.f.) trees in a high-density orchard over 6 years in Korea. Adjacent trees in the rows were removed in 2008 (first-year thinning) or in 2010 (gradual thinning). Trees in the second treatment also had 25% of the main scaffold branches removed in the first two seasons. Control plots were left unthinned. First-year thinning elevated leaf macro-nutrient concentrations, increased the production of short fruiting shoots (less than 20cm) per tree, decreased water sprout development and weight of pruned biomass, and increased fruit set compared with values recorded on control trees and with gradual thinning. First-year thinning gave higher photosynthetic photon flux in the centre of the canopy and better fruit quality. There were generally only small differences in total yield across the three treatments in individual years, but much higher total marketable yield from 2010 to 2013 in the first-year thinning plots. First-year thinning improved overall tree productivity, and the gross returns were 80% higher than those of control from 2008 to 2013 when the extra cost of the thinning was taken into account.