Response Of Ten Garden Herbs To Drought Stress-Rehydration In Guangzhou

Drought is one of the important adversity factors affecting the normal growth of plants.Herbs,as ornamental plants commonly used in landscape greening,are widely used in landscape plant allocation and have a high frequency.Therefore,the research on the tolerance of garden herbs to drought stress is still one of the hotspots of plant stress resistance.Lingnan region has comparatively abundant water resources,but in the accelerated expansion of the city,the development and construction of the river water environment does not pay attention to,resulting in serious water pollution and water quality shortage.The large amount of water needed for urban green space construction has made water resources more scarce,and the contradiction between supply and demand of water resources in Lingnan region has become increasingly prominent.Screening and popularizing grass cover plants with strong drought resistance is of great practical significance for alleviating the tension of urban water use,improving the severe ecological situation and restoring the environment.In this study,the plant resources of ecological revetment in Guangzhou were investigated and analyzed.The results showed that Araceae,Liliaceae,Lycoridae and Iridaceae appeared frequently.Combining with literature search and expert consultation,we selected Dianella ensifolia‘WhiteVariegated',Aspidistra elatior Blume,Hymenocallis littoralis,Crinum asiaticum,Curculigo capitulata,Belamcanda chinensis,Iris tectorum.,Philodendron selloum,Philodendron cv.Xanadu,and Syngonium podophyllum were the ten garden herbs studied in response to drought stress and rehydration.Under natural drought treatment,soil water content and plant morphology were measured at 0d,4d,8d after drought,4d and 8d after rehydration.Physiological indexes,photosynthetic indexes and chlorophyll fluorescence kinetic parameters such as relative chlorophyll SPAD value,SOD,MDA,net photosynthetic rate,stomatal conductance and maximum photochemical quantum yield were measured respectively.Principal component analysis was used to reduce the dimension of the index data,and five principal components were obtained to evaluate the drought resistance of plants comprehensively.The results show that:?1?The trend of soil water content under drought stress is similar as a whole.Water retention of different plants may affect the change range of soil water content in the mid-term of drought stress,indicating that the intensity of experimental conditions of several garden herbs under drought stress is basically the same.In the same place and control test conditions are basically the same.?2?The morphological changes of plant drought,with the increase of drought,plants appeared wilting,darkening leaves,yellow leaves and other phenomena.After rehydration,the leaves of Phyllostachys argentea and Phyllostachys argentea recovered more obviously,while the leaves of other plants withered and grew new leaves to supplement.?3?With the increase of drought stress time,the water content,relative chlorophyll content and SOD of leaf tissues decreased in different extent,but the trend of soluble sugar and MDA was opposite with the degree of rehydration.In terms of photosynthetic fluorescence index,net photosynthetic rate,stomatal conductance,intercellular CO₂ concentration,transpiration rate,maximum photochemical quantum yield,actual photochemical quantum yield,photosynthetic electron transfer rate and photochemical quenching coefficient decreased,while non-photochemical quenching coefficient increased.After rehydration,the former increased and the latter decreased gradually.According to the results of principal component analysis,the larger the calculated score,the stronger the drought resistance of the corresponding plants,and vice versa.The ranking of drought resistance of 10 garden herbs ranked from high to low in the order of Dianella ensifolia‘WhiteVariegated'>Hymenocallis littoralis>Iris tectorum>Syngonium podophyllum>Philodendron cv.Xanadu>Belamcanda chinensis>Philodendron selloum>Aspidistra elatior Blume>Crinum asiaticum>Curculigo capitulata.Among them,the drought resistance of Araceae taro and angel is better than that of spring plumage,which can be used as a reference for the selection of plant allocation.