Selection And Study Of Adaptive Herbaceous Plants In Sunken Greenbelt In Shenzhen

Sunken green space is an important part of rainwater control measures for low impact development,which has the function of reducing rainwater runoff and slowing down the flow velocity of rainwater.As the basic elements of the sinking green space,plants play the role of purifying and retaining the pollutants in the rainwater.The ability of flood tolerance and rainwater purification are the key to plant selection for sinking green land.By summarizing and investigating the effects of plant function and environmental factors,10 kinds of herbaceous plants were selected as the research object,and the effects of water stress on the physiological indexes of plant leaves were measured.Compared with the control,the chlorophyll content of 10 plants decreased significantly after 28 days of flooding（p<0.05）.In the aspect of the membrane systems,the relative conductivity and MDA content of Nephrolepis auriculata,Ruellia brittoniana,Ophiopogon bodinieri,Syngonium podophyllum and Hedychium coronarium were increased significantly（p<0.05）.In the aspect of the cell osmotic regulation,the soluble sugar content and proline content of Nephrolepis auriculata,Syngonium podophyllum and Hedychium coronarium were significantly decreased（p<0.05）,while Dianella ensifolia had no significant change（p>0.05）.In the aspect of anti-dehydration ability,there were no significant change（p>0.05）inAspidistra elatior,Iris tectorum and Dianella ensifolia,but the other all had significant decrease（p<0.05）.In the aspect of antioxidant enzymes,the activities of SOD,POD and CAT in Hedychium coronarium,Iris tectorum and Ophiopogon bodinieri were significantly increased（p<0.05）.At the same time,we compared the ability of different plants to purify rainwater within 3 days,there was no significant difference in the removal ability of SS in the rainwater among 7 plants.Alpinia zerumbet and Hedychium coronarium had the best removal effect of NH₄⁺-N in rainwater.Hedychium coronarium,Ruellia brittoniana and Iris tectorum had the best removal effect of TP in rainwater.Ruellia brittoniana,Alpinia zerumbet,and Canna indica had the best removal rate of TN in rainwater.Ruellia brittoniana,Alpinia zerumbet,and Hedychium coronarium had the best ability to remove COD in rainwater.Ruellia brittoniana,Alpinia zerumbet,and Hedychium coronarium were more able to removal of BOD in rainwater.In order to better compare the comprehensive ability of 10 plants in waterlogging tolerance and decontamination ability.Membership function analysis,principal component analysis and cluster analysis were carried out to evaluate their waterlogging tolerance and decontamination ability.Finally,plants with high ability of waterlogging tolerance and decontamination were selected to be popularized and applied.The results show that:1.The 10 herbaceous plants can be divided into three types according to their tolerance to flooded environment:Iris tectorum and Ophiopogon bodinieri are submergence tolerant plants.Hedychium coronarium,Ruellia brittoniana Leonard,Aspidis-Tra elatior,Canna indica,Alpinia zerumbet are medium submergence tolerant plants.Nphrolepis auriculata,Syngonium podophyllum,Dianella ensifolia are intolerant plants.2.The 7 herbaceous plants can be divided into three types according to their ability to purify pollutants in rainwater:Ruellia brittoniana Leonard is the highly purified plants.Iris tectorum,Canna indica and Alpinia zerumbet are moderately purified plants.Hedychium coronarium,Aspidistra elatior,Ophiopogon bodinieri are low purification plants.3.Comprehensive analysis of water tolerance and purification ability model indicate properties the order of 7 herbaceous plants with adaptive from strong to weak are:Ruellia brittoniana Leonard,Iris tectorum,Hedychium coronarium,Canna indica,Ophiopogon bodinieri,Aspidistra elatior and Alpinia zerumbet.In summary,Ruellia brittoniana Leonard,Iris tectorum,Hedychium coronarium,Canna indica not only have strong ability to withstand flooding,but also have strong purification ability.It is suitable as the alternative plant of Shenzhen sunken green space.