INFLUENCE OF ORCHARD SITE PARAMETERS ON FRUIT-QUALITY OF FUJI APPLE

To elucidate the influence of orchard site parameters on fruit quality of 'Fuji' apple grafted on M. 26 rootstock, the crops from 41 orchards located about Shiwa Town, Iwate Prefecture, Japan were analyzed by the quantification theory (1) 1. High positive correlations were found among total sugar content, titratable acid content, and fresh firmness. Principal component analysis applied to the three characteristics revealed that the first component represented fruit quality, whereas the second, apparent fruit maturity. The orchard site parameters seemed to affect the two components in different ways. The more solar radiation to which the apple trees were exposed, the higher was their fruit quality. On apparent fruit maturity, however, soil texture had greater influence than the quantity of solar radiation. 2. Contents of each sugar were also analyzed by principal component analysis, based on their significant correlations. The first principal component represented total sugars, whereas the second component was the difference between reducing sugar and nonreducing sugar contents. The first component made a major contribution to the difference in total fruit sugar contents among the orchards. Because orchard site parameters affected the first component somewhat differently from that on the second component, they may have influenced fruit sugar composition. 3. Oxidation (browning) of the juice was closely related to the soil type of the orchard. The juice of fruits harvested from trees grown on volcanic ash and alluvial soils did not brown as fast as juice of fruits collected from trees grown on red-yellow soils. The browning tendency was seemingly related to the soil nitrogen content.