The Relationship Between Soil Microbial Communities,Plant Nutrition,Physiological Characters And Carya Cathayensis Canker Disease And Soil Regulation

Carya cathayensis is an endemic plant in China where its precious dried fruit is usually used to produce oil.C.cathayensis is widely planted in Lin'an,Zhejiang.In recent years,the C.cathayensis canker disease has become more serious and brought huge ecological and economic losses in forestry.Therefore,it is essential to explore the underlying mechanisms of the C.cathayensis canker disease to find effective management measures for solving the disease problem.To these ends,we investigated the effects of C.cathayensis canker disease on the nutrients and microbial communities in soils and plants,and how different treatments improve the soil environment.Specifically,we i)compared the physiological indexes and nutrients in the cortex of C.cathayensis trees with different age and disease degree;ii)compared the nutrients and microbial communities in soils under C.cathayensis trees with different age and disease degree;iii)studied the changes in nutrients and microbial communities in soils under different treatments(adding limestone,fermentation broth of bacillus and compound microorganism fertilizer)in a greenhouse experiment.The main results were as follows:(1)Soil survey in C.cathayensis stands in Lin'an showed that the nutrient contents greatly exceeded the standard nutrient index.The soil pH that varied from 5.30 to 5.80 was below the optimum pH.The bacterial abundance and diversity decreased significantly with increasing disease severity in C.cathayensis stands(P<0.05);(2)The physiological and biochemical measurements of C.cathayensis cortex indicated that the tree metabolism could be influenced by canker disease.The total phenol and Ca content increased with the increasing disease severity in C.cathayensis stands.However,the contents of polyphenol oxidase,soluble protein,Mg and B decreased.Due to the changes,the resistance ability of C.cathayensis decreased and the plant caught the disease more easily;(3)The results of greenhouse experiment showed that the soil pH could be raised through adding limestone.The fermentation broth of bacillus treatment increased soil nutrient contents and bacterial abundance,and decreased bacterial diversity.The compound microorganism fertilizer treatment increased nutrient contents and fungal abundance,and had no obvious effect on the diversity.Results from present study indicate that the physiological and biochemical index associated with disease resistance changed obviously.Furthermore,the factors that soil acidification caused by excessive nutrient input and microbial environment which had been changed could effect the disease resistance of C.cathayensis stands.In the future,we could do some measures like using special fertilizers to change the C.cathayensis' s metabolism and improve the soil environment conditions so that we could prevention and treatment of C.cathayensis canker disease to some extent.