モモ果実のポリフェノール含量に及ぼす樹勢の影響

Abstract

Peach fruits having an astringent flavor are prevalent in some orchards. This investigation was conducted to establish whether or not a relationship exists between phenolic contents as a measure of astringency and tree and/or scaffold branch vigor.Based on shoot growth, weak and vigorous (normal) 'Hakuto' peach trees growing in the same orchard were selected for study. At harvest, fruits from weak and vigorous trees were analysed for their phenolic contents. There were no significant difference in phenolic contents between fruits from weak and vigorous trees.Phenolic contents of fruits harvested from two scaffold limbs which choked (girdled) with hanging rope or from a scaffold limb which lost nearly all its leaves prematurely were compared to fruits harvested from normal scaffold limb (s) in each 'Hakuto' tree trained to 3-scaffold vase shape. The phenolic contents in fruits from abnormal scaffold limbs and especially those fruits from choked ones were significantly higher than those from the normal scaffold limbs.When the lateral bearing branches of 'Shimizu-hakuto' peach trees were girdled at Stage 1, 2, and 3 of fruit growth periods, the phenolic contents of fruits from the earlier treatments were higher than in those fruits from branches girdled at Stage 3 or the nongirdled control branches. L-phenylalanine ammonia-lyase (PAL) activities were correspondingly higher in fruits from branches girdled at Stage 1 and 2 than were the activities in fruits on non-girdled control branches or those girdled in Stage 3.The possible relationship between these findings and the occurrence of astringent peach fruit is discussed.