Abstract
The copper concentrations of plant parts of one-year-old Japanese black pine (Pinus Thunbergii p.) seedlings treated with excessively applied copper (CuCl2) solution and the copper concentrations of soils (0.1 N HCl extractable) in pots used were investigated. The concentrations of copper solution applied to the soils were 0, 40, 120, 260, 430 ppm.
The results are summarized as follows:
1) The copper concentrations of soils treated with excessively applied copper decrease with the course of time and these decreasing curves are expressed by exponential functions. The higher the treatment concentration, the greater the gradient of decrease becomes.
2) The copper concentrations of plant parts of control group change with the advance of the seasons. It seems that they are high in the early growing season or the formative season and show a tendency to decrease and become slightly high in the late growing season again. The order of concentrations of plant parts is winter bud>root>hypocotyl>epicotyl・leaf in all seasons though thay have respectively the width of fluctuation. ("epicotyl" refers to the stem part above the cotyledon.) Dead leaf is higher than epicotyl and leaf, but the fluctuation is sharp.
3) The order of concentration of plant parts is root>winter bud>epicotyl>hypocotyl>dead leaf>leaf (High concentration treatments). The concentrations of root, winter bud and epicotyl increase from low concentration treatments but that of hipocotyl, dead leaf and leaf begine to increase in high concentration treatments. (over 300 ppm-root concentration)
4) The concentration of dead leaf is higher than that of leaf because dead leaf is made of cotyledon and juvenile leaf in the early growing season whose concentrations are high. The concentration of leaf scarcely increase and is 30 ppm at the utmost in high concentration treaments but that of dead leaf increases over 100 ppm. It seems that plant drifts leaves whose copper concetrations are high and it excretes copper.
5) It is prospected that increase of copper concentration in winter bud and epicotyl from low concentration treatments prevents plant from growing in next year.
