连作香蕉园生态熏蒸剂的筛选及其对土壤微生物群落结构的影响

通过对多年连作后发香蕉枯萎病土壤进行熏蒸处理,应用传统涂布计数法,结合变性凝胶电泳(Denaturing gradient gel electrophoresis,DGGE)技术,较为全面地研究了不同熏蒸剂对病原菌的杀灭效果以及对土壤微生物区系的影响,为连作蕉园的可持续栽培提供了理论依据。试验通过研究石灰、碳铵、石灰碳铵联用、二氧化氯、次氯酸钠、过氧化氢和氨水处理对水体病原菌孢子、土壤中尖孢镰刀菌的杀灭作用,逐步筛选出适合连作蕉园灌溉水和土壤的熏蒸剂种类。结果表明:上述熏蒸剂对水体或土壤中尖孢镰刀菌均具有杀灭作用,土壤中氨水、石灰碳铵联用处理效果更加显著,被选择为发病蕉园土壤熏蒸剂。不同用量氨水、石灰碳铵联用处理熏蒸土壤,随着熏蒸剂施用量的增加,土壤中尖孢镰刀菌数量下降幅度逐渐增大;两种熏蒸剂对土壤中可培养总细菌和总真菌均有杀灭效果,随着用量的增加,总真菌数量下降幅度显著高于总细菌。DGGE结果显示,氨水、石灰碳铵联用处理对土壤中总真菌种类的影响也显著高于总细菌,随着熏蒸剂用量的增加,总细菌有少许条带的增加或减少,总真菌条带丰富度急剧减少。与对照相比,各熏蒸剂处理后总细菌物种多样性指数均有所降低,随着用量的增加,总体呈下降趋势,在氨水、石灰碳铵联用用量分别为2.67 ml/kg和(3.33+1.67)g/kg时各项指数最高。综上,所有熏蒸剂均能作为水体病原菌杀灭剂,其中氨水、石灰碳铵联用是良好的连作蕉园土壤熏蒸剂,最适用量分别为2.67 ml/kg、(3.33+1.67)g/kg。

Screening Eco-fumigants for Banana Orchards with Serious Fusarium wilt Disease and Their Influences on Soil Microflora

In order to screen ecological fumigants for ensuring banana sustainable cultivation in monoculture banana planting orchard, effects of fumguation with different chemical compounds on the number of Fusarium oxysporum f. sp. cubense race 4 (FOC) in water and banana orchard soil and on the soil microflora were studied using the traditional plate-counting method combined with polymerase chain reaction denaturing gradient gel electrophoresis (DGGE) in this study. Fumigants included lime, ammonium bicarbonate, the mixture of lime and ammonium bicarbonate, chlorine dioxide, sodium hypochlorite, hydrogen peroxide and ammonia water. Results showed that all kinds of fumigants mentioned can kill the spores of FOC in the water, while in the soil, ammonia water and the mixture of lime and ammonium bicarbonate showed more effective antifungal effect than other fumigants. Thus, these two kinds of fumigants were selected for further study. Experiments of different dosages of ammonia water and the mixture of lime and ammonium bicarbonate in the pot soil showed that the higher dosage of fumigants added, the better antifungal effect was observed. Both the two kinds of fumigants used decreased the culturable bacteria and fungi amounts, and the decline for bacteria is significantly lower than the fungi. As shown in DGGE, fungal bands were more influenced compared to the bacteria regardless of fumgation with ammonia water or the mixture of lime and ammonium bicarbonate, showing the rapid decrease of abundance for fungi that. While for bacteria, some bands appeared and some bands disappeared. Furthermore, compared with the control, the index of richness, evenness, stability and diversity of total bacteria amended with different dosage of fumigants were all decreased and the index is highest in sample treated with 2.67 ml/kg of ammonia water or 3.33 g/kg of lime mixed with 1.67 g/kg of ammonium bicarbonate among the two group treatments. In conclusion, all the results showed all the chemical compounds could be used as fungicide in the water and confirmed that not only ammonia water with the best additive amount of 2.67 ml/kg but also the mixture of lime and ammonia bicarbonate (3.33 g/kg and 1.67 g/kg, respectively) can be used as fumigants in soil.