关键词: 天然更新, 天然更新

Abstract:

The soil nutrient, microorganism population, and tobacco disease were detected and analyzed in tobacco field in limestone area of Jingxi County, Guangxi Province. The results showed that soil pH was on the high side，except for available potassium, there was comparatively rich in organic matter, total nitrogen, and available phosphorus, potassium, manganese, iron, copper and zinc. It meant that soil fertility levels were adequate. And the contents of organic matter and total nitrogen of paddy field were significant higher than that of dry land (P<0.01). The total of microorganism in soil was 1.21×107-9.91×107 cfu/g. And the quantity of bacteria was dominant, followed by actinomyces, and then fungi. The quantity of bacteria in paddy field was significantly higher than that in dry land (P<0.05). For the tobacco disease, the uppermost one was tobacco potato Y virus disease, followed by tobacco black shank, and then tobacco bacterial wilt. Correlation analysis showed that the levels of soil organic matter and total nitrogen were key factors effect on the amount of soil microorganism and bacteria population. While the high rate of diseases infection maybe correlated with available phosphorus level and pH value of the soil.