茶树根际微生物研究

Microbes studies of tea rhizosphere

利用选择性培养基 ,对土壤肥力肥沃、中等、贫瘠茶园的茶树根际细菌、真菌和放线菌进行了分离。根据菌体形态及培养特征、生理生化指标、DNA的 G+Cm ol%值等 ,对根际细菌进行了鉴定和分类。研究了不同肥力、不同茶龄的茶园根际细菌的数量和类群的变化 ;根际真菌的数量变化 ;根际放线菌的数量变化。主要结果为 :土壤肥沃的茶园根际细菌的数量最多 ,土壤贫瘠的茶园数量最少 ;相同土壤肥力的茶园 ,1 0年生茶园根际细菌的数量最多 ,4年生的次之 ,2 0年生的最少。根际真菌的数量 ,土壤肥沃茶园的较少 ,中等和贫瘠茶园的较多。根际放线菌的数量 ,2 0年生茶园的明显高于 4年生和 1 0年生茶园的 ,而且 ,土壤贫瘠茶园的数量较多。从 9种不同类型茶园中分离获得的纯化细菌经鉴定分别属于 2 0个属 ,中等肥力的茶园最适于多数细菌的生长与繁殖 ,类群最为丰富 ,但类群的优势度低于另外两种土壤 ;不同茶龄的茶园随着茶龄的增加 ,肥沃茶园和中等茶园的根际中有较多的细菌类群定殖 ,但 2 0 a茶龄的类群较少 ;

Rhizosphere bacteria, fungi and actinomyces were isolated from rich, normal, and poor soil samples from various types of tea plantations and their population densities and species distributions were studied. The results indicated that rich tea plantation soils had higher rhizosphere microbe population densities than poor tea plantation soils. In the tea plantations of similar fertility, the population density of rhizosphere bacteria varied with cultivation age of the plantations, following a pattern of 10 year>4 year>20 year. The population density of rhizosphere fungi in rich tea plantations was more than that in normal and poor tea plantations. The population density of actinomyces in 20-year tea plantations was significantly higher than that in 4-or 10-year tea plantations; and moreover, poor tea plantation soils had the greatest population density of actinomyces. Bacteria isolated from various tea plantations were classified into 20 genera. Results from rhizosphere microbe identification and diversity analysis indicated that in rich soil, the diversity index, the richness index, and the domination index of rhizosphere bacteria varied with cultivation age of the plantations, following a pattern of 10 year>4 year>20 year; however, the evenness index varied with cultivation age of the plantations, following a pattern of 20 year>4 year>10 year. In the normal tea plantations, the diversity index and the richness index varied with cultivation age of the plantations, following a pattern of 10 year>4 year>20 year; while both the domination index and the evenness index showed a pattern of 20 years>4 year>10 year. In poor tea plantation soils, the diversity index, richness index and evenness index gradually diminished with the increase of the cultivation age while the domination index increased gradually with the increase of the cultivation age. In 4-year tea plantations, normal soils had the highest diversity index, rich soils the second, and poor soils the smallest; rich and normal soils had similar richness indexes, and both were higher than that in poor soils; the evenness index gradually increased as the soil fertility decreased; the domination index was the largest in poor soils, lower in rich soils, and the lowest in normal soils. In 10-year tea plantations, both the diversity index and the richness index were the highest in normal soils, lower in rich soils, and the lowest in poor soils; the evenness index gradually increased as the soil fertility increased; the domination index was the highest in poor soils, lower in rich soils, and the lowest in normal soils. In 20-years tea plantations, the diversity index and the evenness index were the highest in normal soils, lower in rich soils, and the lowest in poor soils; the richness indexes in rich and normal soils were similar, and both were higher than that in poor soils; the domination index was the highest in poor soils, lower in rich soils, and the lowest in normal soils. These results showed that both soil fertility and cultivation age have impacts on bacteria distribution in the plant rhizosphere. The normal soils provide suitable growth micro-environments for most bacterial genera, implied by the largest number of bacterial genera and the lowest domination index. In poor soils, relatively few bacterial genera can colonize due to the lack of nutrition, leading to a high domination index. The cultivation age may have a significant impact on the colonization and growth of bacteria in poor soils.