This study was conducted to examine the apparent free space of Cymbidium kanran root, characteristics of P-32 absorption by roots, translocation from roots to upper parts, and urea permeability of root cells treated with different relative humidities (35%, 50%, 65%, and 90%). In addition, inorganic composition of C. kanran was determined.
1. AFS of C, kanranroots was 0.44∼0.50m1/g, fresh weight, being rather larger than those of most higher plant roots.
2. The phosphate translocation rate of C. kanran roots to leaves was very slow comparing to another higher plants.
3. The phosphate transport from roots to another roots was more active than that from roots to the other parts(shoot or bulb), regardless of old or young roots.
4. Bulbs contained higher amounts of P, Ca, Mn, Zn, and Na than another parts. The contents of Cu, A1 and Mg in roots were higher than in the other parts and more K was in leaves.
5. The lower relative humidity, the higher urea permeability. The quicker permeation of urea in the root cells treated with low relative humidity might be brought about by increase of cell sap concentration and membrane structure alteration induced by water loss.
6. The lower relative humidity, the lower P-32 uptake by roots. This fact indicated that active absorption of phosphate was inhibited by water deficit. The treatment of 90% relative humidity gave the lowest translocation of P-32.
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