Effects Of Waterlogging Stress On The Physiological Characteristics And Secondary Metabolites Of Herbaceous Peony(Paeonia Lactiflora Pall.)

Herbaceous peony(Paeonia lactiflora Pall.)is a perennial herb which belongs to the Chinese peony branch and the herbaceous peony group.It is warm and cold resistant,with wide adaptability.It has both ornamental value and medicinal value.In China,the cultivation of herbaceous peony has a history of more than 4000 years.It is mainly distributed in Jiangsu,Dongbei,Huabei,Shaanxi and other regions.Waterlogging occurs in many parts of the world due to global warming and poor drainage systems.In China,the main areas of herbaceous peony production are prone to waterlogging in the rainy season,especially in the south of China which has a monsoon climate,where precipitation is concentrated and distributed unevenly.Its yield and quality can be affected by waterlogging as it grows and matures.In this study,to explore the mechanism of waterlogging on secondary metabolites and physiological indicators in herbaceous peony,selected the main plant variety which is ‘Taohuafeixue',‘Yangfeichuyu',‘Hongxiuqiu' to simulate waterlogging treatment.We measure the changes of antioxidant enzyme activity and osmotic regulation substances in leaves and roots of herbaceous peony,to observe the morphology of leaves and roots and to analyze the changes of root microstructure.Statistics of plant height,leaf length,leaf width,leaf area,root crown ratio of each treatment stage.We determined the content of paeoniflorin,paeoniflorin,benzoylpaeoniflorin,gallic acid and total flavonoids.This study provided information for making full use of the medicinal value of herbaceous peony and for its production and cultivation under waterlogged conditions.And the main results are as follows:(1)Herbaceous peony has certain waterlogging resistance.The short-term waterlogging treatment can make its physiological indexes and secondary metabolites adapt to the changes of adversity,and can recover after the stress is relieved,and will not cause fatal injury.The waterlogging resistance and recovery ability of ‘Taohuafeixue' were the strongest,that of‘Yangfeichuyu' and ‘Hongxiuqiu' were the weakest.(2)After a period of waterlogging treatment,the leaves turn yellow or red,and the roots turn black.The microstructure of the root system changes,the stele become thicker,the cortex cells become larger,and the endodermis cell wall become thicker.The effects are characteristic of genotypes.(3)Waterlogging damage did not significantly affect the plant height,leaf length,leaf width,and leaf area of herbaceous peony.After the waterlogging treatment,the root-shoot ratios of all tested varieties were lower than those of the control,and ‘Yangfeichuyu' and‘Hongxiuqiu' were the most significant.Waterlogging damage has little effect on the growth index of herbaceous peony,and the growth will not be seriously affected.(4)Waterlogging increased the activity of antioxidant enzymes(SOD,POD,CAT)and the content of osmoregulation substances(SSC,SP,Pro).The content of MDA in the root system of ‘Hongxiuqiu' was significantly higher than that of the control,and its injury was more serious.The increase of antioxidative enzymes and osmolytes in the herbaceous peony can resist the stress of waterlogging and reduce the harm of herbaceous peony.(5)Different secondary metabolites have different contents in different parts.The content of paeoniflorin,albiflorin and benzoylpaeoniflorin: root > leaf,the content of gallic acid and total flavonoids: leaf > root.(6)The effects of waterlogging on the secondary metabolites of herbaceous peony vary with varieties and parts.Waterlogging increased the content of paeoniflorin and albiflorin in the root systems of ‘Taohuafeixue' and ‘Yangfeichuyu',increased the content of benzoylpaeoniflorin in the root system of ‘Hongxiuqiu',increased the content of gallic acid and total flavonoids in the leaves of ‘Taohuafeixue' and ‘Yangfeichuyu',and also increased the content of paeoniflorin and benzoylpaeoniflorin in the roots of ‘Hongxiuqiu' in autumn.This experiment mainly studies the effect of waterlogging on the secondary metabolism of herbaceous peony,understands the physiological mechanism of response of herbaceous peony to waterlogging,provides theoretical basis for the production and cultivation of herbaceous peony and the research of secondary metabolites,and improves the application value of herbaceous peony.