Effects of alkaline fertilizer on occurrence of banana wilt disease and soil microbial community

【Objectives】In view of problem of serious declining banana production and even constrained abandon of banana orchards in many regions of China caused by soil acidification, deterioration of microbial community and wide spread of Fusarium oxysporum f.sp. cubense (FOC)in banana plantation, the objective of the research was to study effect of a kind of alkaline fertilizer (AF) as a measure of improving soil pH, ameliorating the microbial community, reducing incidence of the Fusarium and promoting the growth of banana. 【Methods】The effects of the AF on banana wilt disease development and three main types of microorganisms in soil were studied by using pot culture during banana seedling growth with two-groups and three-levels design. The experiment included fertilizer treatments (AF), conventional fertilizer treatments(CCF) and both the AF and CCF consisted of three levels of applied fertilizer N. The total amount of N, P2O5 and K2O used was the same in one level. There were 6 treatments in total. The tested soil was collected from the wilt disease infected banana plantation in Ledong County, Hainan Island, China. After transplanting bananas to nutritive pots for 130 days, the soil and plant samples were collected on 6 March 2013 when the differences of incidence of FOC were significant among different treatments. 【Results】 1) After four times interval fertilization, the incidences of the FOC of the banana treated with the AF are significantly lower than those in the conventional compound fertilizer treatments, which shows a positive result of the AF application during the banana growth, and the incidence of the disease is 78% in the CCF and 33% in the AF treatment. 2) Soil microbial community is significantly affected by the AF mainly in the soil microbial population. The amount of fungi population in the soil treated with the AF is remarkably less than that in the CCF, while the amounts of actinomycetes and bacteria population are significantly higher than those in the CCF treatments. The amount of FOC is decreased significantly after the AF fertilization. 3) The AF fertilization could raise soil pH value significantly during the experiment. The pH values of the soil treated with AF are increased by 0.75 unit compared to the CCF treatment after four-time interval application. Whereas the soil EC of the former treatment is decreased by 47.76 μS/cm compared to the later one. 4) There are significantly negative correlations between the soil pH value and number of FOC, the incidence of the disease respectively. Meanwhile, there are significant negative correlations between the number of bacteria in the soil and number of FOC, disease index of the FOC. However, the incidence of the disease is significantly positive correlated with number of fungi and FOC. 5) The banana biomass is increased significantly with the increases of both AF and CCF applied in the trial, and the effect of AF is greater than that of CCF.【Conclusions】The use of alkaline fertilizer not only provides nutrients such as nitrogen, phosphorus and potassium for banana, but also increases soil pH and improves soil microbial community for promoting actinomycetes and bacteria development. The use of AF will significantly prevent and control the infection of FOC during banana growth.