蚕沙发酵有机肥对连作杭白菊根际细菌群落的影响

Effects of Organic Fertilizer from Fermented Silkworm Excrement Application on Soil Microorganisms of Chrysanthemum Morifolium under Continuous Cropping

[目的]在杭白菊连作3年的土壤上采用小区实验方法施用蚕沙发酵有机肥,探讨施用蚕沙发酵有机肥对连作杭白菊根际土壤细菌群落的影响。[方法]田间实验设置3个处理组,依次为轮作组(杭白菊与玉米进行轮作),连作组(杭白菊连作3年),施肥组(在杭白菊连作田,第3年种植初期每株施用蚕沙发酵有机肥15 g)。在收获期进行采样,用HaeⅢ、HinfⅠ分别进行酶切后,采用末端限制性片段长度多样性(T-RFLP)检测。[结果]连作组、轮作组和施肥组的HaeⅢ酶切后Shannon指数分别为:3.08、3.24、3.24,HinfⅠ酶切后Shannon指数分别为3.31、3.60、3.57,可见连作组的细菌多样性明显低于轮作组和施肥组,说明连作使杭白菊根际细菌生物多样性下降,而轮作和施肥则可显著提高根际细菌多样性水平。对优势菌属进行比对分析发现,不同处理组间有较大的差异。连作组的9种优势菌属中梭酸属(Clostridium)、植原体属(Phytoplasma)、黄单胞菌属(Xanthomonas)为致病菌属;施肥组的8种优势菌属中梭酸属和黄单胞菌属为致病菌属,另6种为有益菌;轮作组的8种优势属中仅有梭酸属为致病属,其余7种均为有益菌。由此推测,施肥和轮作处理均会改变根际细菌群落结构,主要体现在减少致病菌的伤害。此外,在施肥组中还发现有被誉为生防菌的枯草芽孢杆菌(Bacillus subtilis)。[结论]施用蚕沙发酵有机肥,能有效提高连作杭白菊的根际土壤细菌多样性水平,降低病原菌优势,促进功能菌和有益菌的生长,通过改善微生态环境缓解连作障碍。

[Objective] Plot and field experiments were carried out to investigate the effect of organic fertilizer from fermented silkworm excrement application on Chrysanthemum morifolium rhizosphere-soil microorganisms under continuous cropping. [Methods] The field of the experiment was already continuously mono-cropped for three consecutive years with Chrysanthemum morifolium. Three treatments were arrayed-Chrysanthemum morifolium was cultured in rotation cropping field（rotation cropping group）, Chrysanthemum morifolium was cultured in continuous mono-cropping field（continuous mono-cropping group）, Chrysanthemum morifolium was cultured in continuous mono-cropping field and application of 15 g per plant of organic fertilizer from fermented silkworm excrement at transplanting period（fertilization group）. Rhizosphere soil samples was collected in harvest period and was detected with T-RFLP（terminal restriction fragment length polymorphism）. [Results] T-RFLP results of Hinf Ⅰshowed that compared with the Shannon index（3.60）of rotation cropping group, continuous cropping group decreased it to 3.31,while fertilization group was 3.57. The results of Hae Ⅲ were 3.24, 3.08, 3.24,respectively. The bacterial diversity of continuous cropping group was obviously lower than rotation and fertilization group, showing that rotation and fertilization can significantly improve the level of diversity of rhizosphere bacteria which caused by Chrysanthemum morifolium continuous cropping.Through the dominant bacteria genera analysis it was found that there were 9 kinds of dominant bacteria genera in continuous cropping group, which respectively belonged to Bacteroidetes, Firmicutes, Proteobacteria, Tenericutes, Gracilicutes and Actinobacteria, among them Clostridium, Phytoplasma and Xanthomonas were pathogenic bacteria; 8 kinds of dominant bacteria genera in the fertilization group which respectively belonged to the Bacteroidetes, Actinobacteria, Firmicutes, Proteobacteria and Gracilicutes, among them only remaining pathogenic bacteria genera were Clostridium and Xanthomonas; 8 kinds of dominant bacteria genera in the continuous cropping group respectively belonged to the Bacteroidetes, Firmicutes and Proteobacteria, Clostridium were the only detected pathogenic bacteria. These results showed that fertilization and crop rotation processing will change the rhizosphere bacteria community structure mainly through reducing bacterial pathogens. Interesting founding was that Bacillus subtilis called biocontrol bacterium was detected in fertilization group. [Conclusion]The application of organic microbe fertilizer can effectively improve rhizospheric bacterial diversity of continuous cropping of Chrysanthemum morifolium, reduce the advantages of pathogens bacteria and promote the growth of beneficial bacteria.