|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1995 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1994 : ¥1,700,000 (Direct Cost : ¥1,700,000)
The objectives of this study are to find an interaction of transpiration rates with salt absorption and to evaluate the ability of parenchyma cells in xylem to uptake the absorbed sodium through root from soil and to discuss the differences of the salt tolerance among woody species.
One year old seedlings of six species of woody non halophytes were irrigated with five different concentration of NaCl (0, 13, 25, 50, and 100mM) for 50 days. The daily transpiration were measured using weighing method and the rates of photosynthesis and transpiration, and stomatal conductance were also measured. At the end of experiment, the concentration of cations and anions of the leaves, stem, and fine roots and basal roots were determined. The results obtained were as follow ; the reflection coefficient, an index of controlling the sodium absorption in roots, were determined with a bulk water flow (transpiration) and sodium concentration in soil medium. This values varied among species and were considered as one of the important parameters of salt tolerance of species.
The roots of Rhododendron simnii had a very limited capacity of holding the absorbed sodium, then the rest of them flowed into leaves. Consequently, this is considered as sodium non excluder. On other hand, Robinia pseudoacasia, Cychlobalanopsis myrsinaefolia, and Pasania edulis were considered as sodium excluder which can hold sodium in roots and stems and the amount of sodium in leaves were very low. Ternstroemia gymnantheria and Pinus thunbergii were in the middle of both species.
The existence of Na-K ion exchange in root and stem parenchyma cells in the xylem were infered by a constant rate of ion exchange through six species and organs.