Studies On Endurance Of Three Kinds Of Color-leafed Ground Coverplants Under Waterlogging Stress

In this research,Pilea cadierei,Fittonia uerschaffeltii and Oxalis triangularis’Purpurea’ were used as the experiment materials,four types:control(CK——normal irrigation management and kept the soil moist),root submergence(S1——the root soil was fully immersed in water,and the flooding height was higher than that of the basin soil 2-3 cm),half submergence(S2——root soil was all flooded,flooding over half of the upper part of the plant)and all submergence(S3——the whole plant was flooded,flooded over the soil surface 30-40cm)were applied to simulate waterlogging experiment.6d,12d,18d,24d,30d,36d and 42d seven flooding time levels were set for Pilea cadierei and Fittonia uerschaffeltii,6d,12d and 18d three levels of flooding time were set for Oxalis triangularis ’Purpurea’ to study response characteristics of the morphological characteristics,growth indexes(plant height,number of leaves and leaf area)and some physiological and biochemical indexes(pigment content,membrane permeability characteristics,osmoregulation and antioxidant enzymes and so on)of three kinds of color-leafed ground coverplants under different flooding conditions.Using single factor analysis of variance,we obtained the effects of different flooding treatments on the every index of these three kinds of plants.Then,principal component analysis and fuzzy membership function method were used to overall evaluate the water-tolerant ability,in order to provide reference of Chengdu city color-leafed ground coverplantss application,at the same time,to improve the contents of these three plants.The main results were as follows:(1)With increasing inundation duration,the three kinds of plant morphological characteristics gradually appeared scorching,wilting,lodging and other changes,the degree and time of changes were also different in different plants types and degree of waterlogging:the injuried degree of Pilea cadierei and Fittonia uerschaffeltii,from severe to mild was:all submergence>root submergence>half submergence>control,but Oxalis triangularis ’Purpurea "s injuried degree was all submergence>half submergence>root submergence>control;Oxalis triangularis ’Purpurea’ appeared lodging only 6 days,which is the earliest emergence of lodging under all submergence treatment,while Fittonia uerschafeltii was to reach the 24 days before lodging.(2)Under waterlogging stress,the height,leaves number and leaf area of the three plants were changed significantly(P<0.05),vegetative growth of the three plants were compared with the control group difference.At the same time,the vegetative growth of the three plants were seriously affected by the total submerged treatment:the forty-second day,the leaves number of Pilea cadierei was 90.77%lower than that of control,and at this time,existing leaves were the top of the newly developed leaves;the leaves number of Fittonia uerschaffeltii reduced by 48.15%;While,Oxalis triangularis ’Purpurea’was all died in the eighteenth day.(3)The chlorophyll content of Pilea cadierei and Fittonia uerschaffeltii in waterlogging treatments decreased,the overall lower than the control;The chlorophyll content of Oxalis triangularis’Purpurea’ in root submergence and half submergence decreased first and then increased,the content of all submergence continued to decline,the twelfth day’s content decreased 66.56%,which compared with the control.With the continuous waterlogging stress,the anthocyanin content of Pilea cadierei and Fittonia uerschaffeltii increased first and then decreased,but Oxalis triangularis’Purpurea’continued to decline,were lower than control plants,in the twelfth day,all submerged plants decreased 70.44%,which decreasing level of anthocyanin content was the largest amount.(4)With the continuous waterlogging,the free proline(Pro)content of the three plants first increased and then decreased,under the root submergence and all submergence,Pilea cadierei reached the peak at the sixth day,and reached the peak under half submergence at the thirty-sixth day.Fittonia uerschaffeltii in the full submergence of the thirtieth day reached the peak,semi submergence and root submergence all reached peak in the twelfth day,the Pro content of Oxalis trianglaris ’Purpurea’ under the all submergence and half submergence and root submergence peaked in the sixth day,that illustrated Oxalis triangularis ’Purpurea’ suffered waterlogging earlier,submergence tolerance is poorer.(5)With increasing inundation duration,the soluble sugar content of Pilea cadierei’s leaves increased first and then decreased;The soluble sugar content of Fittonia uerschaffeltii firstly increased and then decreased in the case of root submergence and semi submergence,it decreased firstly and then increased in the case of full submergence.The soluble sugar content of oxalis triangularis’Purpurea’ showed a downward trend in waterlogging treatment.Oxalis triangularis ’Purpurea’ increased 58.12%,which is the largest volume,Fittonia uerschaffeltii increased 19.24%,which is the the lowest.(6)With the extension of waterlogging time,the relative conductivity of the three plants showed a trend of increasing first and then decreasing.At the end of the period,the relative conductivity of the leaves of the three plants was all submergence>semi submergence>root submergence>control.The malondialdehyde(MDA)content of Pilea cadierei showed an increasing trend under waterlogging.The content of MDA increased by 215.69%which compared with the control in the thirty-sixth day;The content of MDA in the leaves of Fittonia uerschaffeltii decreased firstly,and then decreased.It was reduced by 56.99%under full submergence;The MDA content of Oxalis triangularis ’Purpurea’ in waterlogging treatment continued to decrease,when flooded with the sixth day,the content was higher than the control,the content of MDA decreased 18.87%at the end of full submergence.(7)With the stress time prolonging,the superoxide dismutase(SOD)activity of Pilea cadierei and Fittonia uerschaffeltii firstly increased and then decreased,At the end of full submergence,the SOD activity of Pilea cadierei decreased by 11.86%compared with the control,the SOD activity of Fittonia uerschaffeltii increased by 47.67%,the SOD activity of Oxalis triangularis ’Purpurea’ increased by 35.76%.(8)Utilizing principal component analysis,three principal components which effected the ability of waterlogging resistance of the three plants were extracted,the first principal component was the number of leaves,anthocyanins,soluble sugar and malondialdehyde;the second principal components was leaf area,superoxide dismutase;the third main ingredients was chlorophyll.Cumulative contribution rate reached 90.125%,which represented the vast majority of information.The comprehensive evaluation about waterlogging tolerance of three plants was made by the fuzzy mathematics subordination function method,which showed that waterlogging tolerance ability from high to low was Fittonia uerschaffeltii>Pilea cadierei>Oxalis triangularis ’Purpurea’.