Effect of Drought Hardening in Earlier Growing Stage on Water Utilization Efficiency of Millet A Comparative Study of Photosynthetic Characteristics of Caragana davazamcii Between Plants of Different Ages in Huangfuchuan Basin of Ordos Plateau SEASONAL CHANGES OF PHOTOSYNTHETIC CHARACTERISTICS IN 12 TREE SPECIES INTRODUCED ONTO OIL SHALE WASTE Study on Photosynthesis and Water Physiology of Cinnamomum septentrionale Influence of VA Mycorrhize on Nutrient and Water Absorption in White Clover Characteristics of Photosynthesis and Water Physio-ecology of Young Macrocarpium officinalis Effects of water and fertilization on relationship between competitive ability and seed yield of modern and old spring wheat varieties THE EFFECT OF RARE-EARTH ELEMENTS ON PHYSIOLOGICAL CHARACTERISTICS OFROBINIA PSEUDOAEACIO SEEDLINGS CHARACTERISTICS AND MECHANISM OF DROUGHT TOLERANCE Of PLATlYCLADUS 0RJENTALJlS PROVENANCES Effects of silicon application and drought stress on photosynthetic traits and mineral nutrient absorption of rice leaves Study on Suitable Irrigation Norms of Pinus tabulaeformis and Platycladus orientalis Plantation