Effects Of Drought Stress On Growth,Physiology And Secondary Metabolites Of Saposhnikovia Divaricata Seedlings

Drought stress has the greatest impact on plant growth and development,which seriously restricts the development of economy and production in Northwest China.It is significant to search for drought resistant plants and study the drought resistance mechanisms to alleviate the local drought.Saposhnikovia divaricata(Turcz.)Schischk belongs to the Umbelliferae family,which is rooted in medicine.The plant has the characteristics of cold and drought resistance and Inner Mongolia is one of its real estate areas.The planting of Saposhnikovia divaricata is mainly based on artificial cultivation,but improper control of the moisture during cultivation process will lead to a decrease in the yield and quality of the plant.In this study,we used potted Saposhnikovia divaricata seedlings as experimental materials,through short-term drought stress in different seasons and secondary drought stress treatment to discuss the adaptation mechanism of the plant to drought,and to explore whether a certain degree of drought stress can promote the improvement of Saposhnikovia divaricata quality.The results are as follows:1.Drought stress in summer was more severe than that treated with the same days in autumn.Severe drought stress significantly reduced biomass(fresh and dry weight of shoot and root)and root diameter of Saposhnikovia divaricata.However,there was no significant change in root length,lateral root number and basal leaf number under progressive drought stress.The results showed that Saposhnikovia divaricata had strong tolerance ability to drought,and only severe drought stress affected its growth.2.Malondialdehyde,glutathione,proline and soluble sugar content in leaves and roots as well as leaf electrolyte leakage increased significantly from moderate drought stress.Hydrogen peroxide content only increased significantly under severe drought stress and catalase activity showed a tendency to increase first and then decrease.The results showed that drought stress induced oxidative damage,and Saposhnikovia divaricata resisted drought by activating antioxidant system and accumulating osmolytes.3.The two chromone components increased significantly from moderate drought stress.After rehydration,the levels of prim-O-glucosylcimifugin and 4′-O-β-D-glucosyl-5-O-methylvisamminol still maintained significant differences with the control group.It indicated that Saposhnikovia divaricata responsed to drought stress by accumulating secondary metabolites.4.By GC-MS determination,23 and 14 volatile components were obtained in the autumn drought stress and secondary drought stress experiments.Among them,aromatic alcohol compounds occupied a large proportion.As a characteristic volatile component,falcarinol relative content decreased significantly under severe drought stress.In summary,we believe that moderate drought stress is beneficial to improving the quality of the herb.