| Water deficit is one of the major limiting factors in plant growth in the mountains and hills of Shandong. Forsythia suspensa(Thunb.) Vahl, Euonymus fortunei(Turcz.) Hand.-Mazz and Lonicera japonica Thunb. are common afforestational tree species in this region. While the mechanisms for the physiological change in different soil drought stress and their drought resistances are not very clear. The objective of this study was to investigate processes and mechanisms of drought stress on the physiological changes of and evaluate the drought-resistant ability of the three tree species. The physiological responses of two-year-old of Forsythia suspensa(Thunb.) Vahl, Euonymus fortunei(Turcz.) Hand.-Mazz and Lonicera japonica Thunb. to soil drought stress were investigated by natural drought method. The results showed that:(1) Three species of net photosynthetic rate and water use efficiency were higher in the soil relative water content range in 30%- 70%, 40%- 50%, 40%- 50%, respectively.(2) When soil water content was 20%-30%、40%-50%、40%-50% stomatal limitation of net photosynthetic rate of the three tree species changed non-stomatal limitation, respectively.(3) Malondialdehyde content of Forsythia suspensa(Thunb.) Vahl, which under stress conditions was significantly higher than Euonymus fortunei(Turcz.) Hand.-Mazz and Lonicera japonica Thunb., in addition, the change regularity between malondialdehyde content and relative membrane permeability is not consistent.(4) The chlorophyll content of all the three species was stable, and the content of Lonicera japonica Thunb. was significantly lower than Forsythia suspensa(Thunb.) Vahl and Euonymus fortunei(Turcz.) Hand.-Mazz.(5) The proline content and superoxide dismutase activity of all the three species were increased greatly, when they were drought stress. In short, the drought resistance of Forsythia suspensa(Thunb.) Vahl is best, Euonymus fortunei(Turcz.) Hand.-Mazz,and Lonicera japonica Thunb. are the next. |
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