Study On Drought Resistance Of Clematis Heracleifolia And Nepeta Cataria

Ground cover plants play a key role in urban green space.They are indispensable plant elements in garden landscaping all over the world,and their application in green space is also increasingly prominent.However,drought is a common problem in garden greenland.Therefore,the development and utilization of drought resistant ground cover plants can not only provide more drought resistant ground cover plants,enhance the ornamental of green space,but also has a significance meaning in cutting costs in maintenance and management,protecting the environment and saving water resources.In this experiment,Clematis heracleifolia and Nepeta cataria were used as the materials to discuss the impact of different drought treatment on morphological,physiological and photosynthetic fluorescence of potted plants?normal watering,mild stress,moderate stress,severe stress?and field cultivated plants?normal watering and drought?.The main results are as follows:?1?Drought stress inhibited the growth of two ground cover plants.Under the condition of pot culture,the plant height and leaf area of Clematis heracleifolia and Nepeta cataria decreased with the increase of drought degree.Under the condition of ground planting,the plant height and leaf area of two ground covered plants under continuous drought treatment were lower than those of the control.With drought treatment,leaves and new shoots of Clematis heracleifolia and Nepeta cataria were damaged,after rewatering,the damage recovered.?2?Drought treatment hindered the accumulation of biomass of two ground cover plants.With the aggravation of drought,the root biomass,above ground biomass and total biomass of Clematis heracleifolia and Nepeta cataria decreased gradually,the root-shoot ratio increased gradually.There was a significant difference between the total biomass of two kinds of plants which was under severe drought stress and those control group.?3?With the increase of drought stress,the water content,chlorophyll?a,b,a+b?and carotenoids content in Clematis heracleifolia and Nepeta cataria leaves gradually decreased;the content of electrical conductivity,proline and MDA in the leaves of two plants increased.Under the condition of ground planting,the water content,chlorophyll?a,b,a+b?and carotenoids of the leaves of two plants with drought treatment were lower than those of the control,and the electrical conductivity was higher than that of the control.?4?Chlorophyll fluorescence of two ground cover plants changed under drought treatment.When the drought treatment was 20d,the Fm,Fv/Fm,Fv/Fo,?Po,?o and?Eo of Clematis heracleifolia and Nepeta cataria under pot culture condition gradually reduced with the increase of drought degree.The Fo,ABS/RC,TRo/RC,ETo/RC,DIo/RC increased with the increasing degree of drought.The Fm,Fv/Fm,Fv/Fo,?Po,?o and?Eo of two ground cover plants were lower than those of the control under ground planting condition.The Fo,ABS/RC,TRo/RC,ETo/RC,DIo/RC of the ground cover plants were higher than those of the control.?5?Drought treatment had an effect on the photosynethetic characteristics of two ground cover plants.With the drought treatment for 20d,the net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?Gs?,and intercellular CO₂ concentration?Ci?of two potted plants decreased with the increase of drought stress and the net photosynthetic rate,stomatal conductance,transpiration rate and intercellular CO₂ concentration of two ground cover plants in the arid area were lower than those of the control under the condition of ground planting.Under drought condition,the net photosynthetic rate,stomatal conductance and transpiration rate of two ground cover plants changed as"Double peak"type and the overall diurnal variation trend of intercellular CO₂ concentration decreased first and then increased.