Abstract:Influence of different phosphorus levels on some biochemical characteristics in phosphorus-starved Cymbidium sinense (Andr.) Willd. was studied. It was found that the amounts of inorganic phosphoric acid, phosphatidic acid, inositol hexaphosphate, hexose phosphate, high-energy phosphate compound and nucleic acid in plant were increased to different extent with increasing NaH2PO4 concentration. The acid phosphatase activity negatively related to phosphorus concentration, and NaH2PO4 at 0. 02 mmol/L may basically satisfy the requirement of the plant growth. We observed that leaf had lower contents of protein and soluble sugar and higher contents of free amino acid and starch during phosphorus deficiency. Hence, the reduction of plant height in C. sinense plant grown in Pi deficiency medium may primarily be caused by the deficiency of Plotein.