カキ‘西村早生’樹の生長，養分吸収，水分ストレスおよび根の呼吸活性に及ぼす新梢伸長初期の環状はく皮の影響

Abstract

The effects of girdling the trunks of 6- to 9-year old, close-planted Japanese persimmon (Diospyros kaki L. cv. Nishimurawase) trees during early shoot elongation period on tree growth and root functions were determined. Girdling (1 cm width) trunks 10 cm above the ground level in early May (23 days before full bloom, DBFB) inhibited current shoot and trunk growth and decreased leaf number per tree. Shoot growth inhibition continued into the next season but had little or no effect on yield and fruit quality in the two years. Girdling the trunks in late April or early May, 34 and 23 DBFB, respectively, revealed that the earlier the tree trunks were girdled, the greater was the inhibition on shoot and trunk growth. Both treatments reduced leaf number per tree and leaf growth. The trunk girdling decreased the respiration rate of fine roots, the nitrate nitrogen and potassium conc. in the xylem sap as well as that and magnesium in the shoot. However, it had a negligible effect on leaf and stem water potential. These results indicate that trunk girdling during early shoot elongation period has a dwarfing effect on close-planted Japanese persimmon trees. Furthermore, it revealed that the growth inhibition was caused by a reduction of dry matter production attributable to the smaller number and areas of leaves and by inhibition of root functions, such as nutrient absorption and accumulation.