Chlorophyll Fluorescence Characteristics of Elaeagnus angustifolia L. and Grewia biloba G.Don var.parviflora(Bge.)Hand.-Mazz. Seedlings under Drought Stress Salt Tolerance of Elaeagnus angustifolia L. and Caragana korshinskii Kom. During Germination DEVELOPMENTAL AND ANATOMICAL STUDIES ON THE FLORAL NECTARIES IN ELAEAGNUS ANGUSTIFOLIA Physiological Characteristics of Different Elaeagnus angustifolia L. Provenances Under NaCl Stress