Dynamic accumulation of saponins in Hedera helix EFFECTS OF COMPOUND POLLUTION OF ZINC AND CHROMIUM ON SOIL ENZYME ACTIVITY AT DIFFERENT GROWTH STAGES OF RICE PLANT Kinetic study on cell wall components for brittleness mutation rice at different growth stages The characters of salt-tolerance at different growth stages in cotton Effects of Shading on Photosynthesis and Yield of Tomato Plants at DifferentGrowth Stages Effects of Shading on Photosynthesis and Yield of Tomato Plants at DifferentGrowth Stages Study on dynamic growth of Codonopsis pilosula