Physiological Characteristics of Elaeagnus angustifolia and Grewia biloba G.Don var.parviflora Seedlings under Drought Stress

Elaeagnus angustifolia and Grewia biloba G.Don var.parviflora 2-year-old seedlings as materials,we used weighing method to set up four level soil moisture.The physiological characteristics of E.angustifolia and Grewia biloba G.Don var.parviflora seedlings were studied.The results showed:(1)Drought stress causing the serious water deficiency in the two species and their natural saturation deficit was three to four times CK under severe stress.At the same drought stress level,E.angustifolia natural saturation deficit was higher than that of Grewia biloba G.Don var.parviflora,but the critical water saturation deficit and requirement level of water were reverse.With the drought stress increasing,free water content of E.angustifolia declined largely,more and more free water turned into the bound water.The highest water potential of E.angustifolia declined in less than that of Grewia biloba G.Don var.parviflora.The lowest water potential was reverse and the absolute water potential of E.angustifolia was lower than that of Grewia biloba G.Don var.parviflora.(2)With drought stress increasing,the contents of proline and total soluble sugar of the two species in the leaves increased to a certain extent.Especially under T3 stress,proline content was higher than that of CK for four times,and Grewia biloba G.Don var.parviflora proline content was significantly higher than that of E.angustifolia,but the total soluble sugar content was less than that of E.angustifolia;With drought stress increasing,the soluble protein content of E.angustifolia firstly increased,and then declined,but Grewia biloba G.Don var.parviflora gradually declined.E.angustifolia itself had a high content of soluble protein,which was less impacted by drought stress.(3)Physiological characteristics of the two species had positive responses to drought stress,speculating the limit of tolerance is 6.4%～8.0%;The species were different in physiological response and E.angustifolia was more advantaged.Therefore,promotion and irrigation management should be treated differently in the future.