Effects Of AM Fungi On Growth And Biochemical Characters Of Glycyrrhiza Under Water And Salinity Stress

Glycyrrhiza is a commonly used herbal drugs and traditional Chinese medicine which has great value in drugs, ecosystem and industry. A serious shortage of wild Glycyrrhiza occurs after years of excessive digging because of its great value. To pursuit economic interests, fertilizers and pesticides are used excessively which pollute environment and reduce Glycyrrhiza's quality. In recent years, it has been proved AM fungi can promote growth of plants under stress and has widly been used as biological fertilizer in agriculture. Therefore, systematic study on relation between AM fungi and glycyrrhiza, especially the effects of AM fungi on physiological and biochemical characters under stress, has important significant for ultilizition of AM fungi, development of glycyrrhiza's planting, increasing glycyrrhiza's quality and protecting encironment.In this resarch, effects of AM fungi on growth, physiological and biochemical characters were studied with greenhouse-grown Glycyrrhiza inflata Bat under varied levels of water and salt. The mainly results showed that:1. Soil water content significantly influenced mycorrhiza infection rate. Inoculation of AM fungi could not only strengthen drought resistence but also promote quality of mycorrhizal plant, especially the root, by raising Mycorrhiza infection rate and contents of flavonoids, N and P in plant. Water stress and AM fungi significantly interacted the quality of host plant but no effect on biomass and external feature. The content of MDA in leaves of inoculated plant was significantly lower than that of non-inoculate plant, that indicated inoculation of AM fungi had reduced injury of water stress by increasing pretective enzymes'activity and osmotica contents. Therefore, AM fungi can significantly promote growth of host plant and strengthen drought resistance of glycyrrhiza. The best inoculation effect occurs under 60% water content which glycyrrhiza grow better.2. Mycorrhiza infection rate was significantly improved by inoculation of AM fungi, but inhibitted by salinity stress. Inoculation of AM fungi could promote growth of host plant and increase biomass and quality of glycyrrhiza and by changing roots'morpha of host plant and improving ability to absorb water and nutrition, especially P. Inoculation of AM fungi also can strengthen salinity resistance by promoting assumulation of osmotica and water preservation in leaves. The assumulation of osmotica induced by AM fungi played an important role in osmotic adjustment to alleviate physiological drought under salinity stress and maintain stable internal environment. Meanwhile, flavonoids content in mycorrhizal plants which can inhibit damage of cell membrane was significantly higher than non-mycorrhizal plants. AM fungi decreased MDA content in glycyrrhiza. Therefore, AM fungi reduced the damage of cell membrane and promote growth of host plant. This resarch suggested that AM fungi can strengthen salinity resistance of glycyrrhiza by assumulation of osmotica and alleviate the cell damages under salinity stress. The best inoculation effect occurs under 0~0.1% salinity content which glycyrrhiza grow better.