Changes of Osmotic Adjustment Substances and Activities of Protective Enzymes in Sedum spurium Coccineum’ Introduced to Xigaze,Tibet Leaf senescence of hybrid spring wheat at flowering and seed formation stage Effects of Soil Salt Stress on the Activity of Protective Enzymes and Peroxidation in Three Warm-season Turfgrasses Responses of fruit quality, leaf protective enzyme systems of tomato to soil water and fertilization