Study On Stress Resistance Of Eight Plants Suitable For Roof Greening

In this study,trees were used as experimental materials to investigate the effects of drought,high temperature and low temperature on Sedum reflexum,Sedum aizoon,Sedum fui,Potentillafragrioides,Potentillaflagellaris,Violaphilippica,Carexbreviculmis,Gaillardia pulchella's growth morphological characteristics,physiology,leaf fluorescence and photosynthetic characteristics,and to measure and research the indicators of these plants under different stresses.It contributes to scientific basis and suitable samples for the screening and management of roof greening plants.The main findings are as follows:?1?Drought treatment had a significant effect on the morphology of the eight plants.The height and crown width of Potentilla fragrioides,Potentilla flagellaris,Viola philippica were significantly increased from 0 to 10 days after drought,while the height and crown width of Sedum fui,Carex breviculmis,Gaillardia pulchella decreased at 15 to20 days after drought.Theheight and crown width of Sedum reflexum,Sedum aizoon have been increasing.?2?Drought treatment had a significant effect on the physiology of the eight plants.With the increase of drought stress time,the conductivity of the eight plants and the trend of proline were consistent,but the soluble protein and soluble sugar showed different trends.In addition to the soluble protein of Potentilla fragrioides,Potentilla flagellaris,Gaillardia pulchella,the soluble protein increased first and then decreased.It is a trend that has been increasing;Potentilla fragrioides,Potentilla flagellaris,Viola philippica,Gaillardia pulchella's soluble sugars increase first and then decrease,and all other plants have been increasing.The change trends of chlorophyll a,chlorophyll b,and chlorophyll a/b in the eight plants were consistent and all decreased with the increase of drought stress time.?3?Drought treatment had a significant effect on the chlorophyll fluorescence parameters of the eight plants.With the increase of drought stress time,the chlorophyll fluorescence parameters of all eight plants increased except Fo,but the values of Fm,Fv/Fm,?Po,and?Eo decreased in turn,and reached a maximum at 10%in soil water content.?4?Drought treatment had a significant effect on the photosynthetic characteristics of the eight plants.With the increase of drought stress time,the net photosynthetic rate,stomatal conductance and intercellular CO₂ concentration of the eight plants decreased with the increase of drought stress time;the diurnal variation of the net photosynthetic rate of the eight plants under drought stress was double-peaked.The curve shows a clear"midday break"phenomenon.?5?Under the high temperature stress,the physiological indexes of the eight plants changed the most is Potentilla fragrioides?Potentilla flagellaris,Sedum aizoon,Sedum fui were moderate;the rest of the plants changed little.The semilethal temperature is Sedum reflexum,Violaphilippica,Carexbreviculmis,Sedumaizoon,Sedumfui,Potentilla fragrioides,Gaillardia pulchella,Potentilla flagellaris in the order from high to low.?6?The relative conductivities of the eight plants were significantly negatively correlated with low temperature.Proline and malondialdehyde were significantly negatively correlated with low-temperature formation,as well as the trend of relative conductivity.It shows that eight kinds of plants have certain resistance to low temperature.Through a comprehensive analysis of eight plants,Potentilla fragrioides,Potentilla flagellaris,Viola philippica can cause wilting in soil moisture content of about 18%,and the cells in the leaves will be destroyed;Sedum reflexum,Carex breviculmis,Gaillardia pulchella the growth condition in the soil water content of about 13%will be inhibited,but not lethal;Sedum aizoon,Sedum fui can adapt itself to arid environment by adjusting itself when the soil moisture content is 10%.Under drought stress,the order of drought resistance of plants from strong to weak was ranked as follows:Sedum aizoon,Sedum fui>Sedum reflexum,Carexbreviculmis,Gaillardiapulchella>Potentillafragrioides,Potentilla flagellaris,Viola philippica.Eight plants can adapt to the summer high temperature environment in Hebei Province and can survive safely.The order of the heat resistance of the plants is in the order of:Sedum reflexum,Viola philippica,Carex breviculmis>Sedum aizoon,Sedum fui>Potentilla fragrioides,Gaillardia pulchella,Potentilla flagellaris.Eight plants can still survive through self-regulation at low temperatures of-15°C,showing strong cold-resistance,and they can all safely pass through the winter cold in Hebei.The order of cold resistance of plants is:Sedum aizoon>Sedum reflexum,Sedum fui,Carex breviculmis>Violaphilippica,Gaillardiapulchella>Potentillafragrioides,Potentilla flagellaris.In summary,the eight plants selected in this experiment can be applied to the greening of Hebei's roofs.The overall performance of the Sedum plant is excellent,the performance of the Carex breviculmis,Viola philippica is general,and the performance of the Potentilla fragrioides,Potentilla flagellaris,Gaillardia pulchella is barely qualified.