C4 Photosynthetic Enzymes and Antioxidant Enzymes Activities in Two Photosynthetic Subtypes of C4 Desert Plants under Soil Drought Stress Changes of photosynthetic pigment and photosynthetic enzyme activity in stems of Phyllostachys pubescens during rapid growth stage after shooting Advances in Flaveria bidentis (L.) Kuntze, A New Exotic Plant High Photosynthetic Efficiency of Leaf Colour Mutant of Rice (Oryza sativa L.)