"秸秆降解生防菌强化技术"(BS)近年在我国北方冬季温室栽培中广泛使用, 具改良土壤、减轻病害、改善品质、提高产量等多方面的效果。为探讨应用该技术后对黄瓜连作土壤中微生物区系的影响, 本研究采用平板培养计数与末端标记限制性片段长度多态性(T-RFLP)分析相结合的方法, 检测了黄瓜连作土壤中真菌、细菌、放线菌以及生防菌和病原菌的数量动态。结果表明, BS处理土壤后, 在连作第2茬时, 土壤中真菌群体总量比第1茬显著减少; 细菌总量比第1茬显著增加。细菌与真菌数量比值(B/F值)在连作两茬时明显升高, 土壤表现为"细菌型"; 连茬土壤中两种生防菌的含量保持相对稳定; 枯萎病原菌数量在连作两茬时与其他处理和对照相比有所降低, 但不显著; 处理后土壤细菌多样性在第2茬时显著升高, 并能促进TRF139等有益菌群增殖, 抑制TRF341和TRF501等有害菌群增殖。BS处理土壤能明显提高连作黄瓜的产量并降低根结线虫的病情指数, 在第3茬时产量比对照增加25.9%, 病情指数比对照减少71.4%。生防菌与秸秆配合使用对黄瓜连作土壤微生物的数量和群落结构影响显著, 在一定的连作茬数内能够保证生防菌有效定殖, 抑制病原菌数量增长, 提高土壤微生物多样性, 使土壤微环境达到相对健康的状态。
Stunted crop growth, yield decline and disease susceptibility have been associated with monoculture cropping. Soil borne diseases have emerged as the main obstacle to continuous cropping, which current biological techniques have failed to overcome. In recent years, however, intensified corn stalk degradation by biocontrol agents has been a widely used technique in winter greenhouses in North China. This technique combining application of crop stalk and biocontrol agents, which can improve soil quality, reduce soil diseases, increase crop productivity, etc. Thus this study aimed to investigate what effects this technique has on soil microbial community in continuous cucumber cropping. The dynamics of fungi, bacteria, actinomycetes, biocontrol agents and pathogens in cucumber fields were determined using both the plate culture counting and terminal-restriction fragment length polymorphism (T-RFLP) methods. The results showed that intensified corn stalk degradation by biocontrol agents significantly influenced soil microbial community in cucumber fields. After treatment, the number of fungi in soils of the second crop (6.33×104 CFU·g-1) was lower than that in the first crop (1.81×105 CFU·g-1) while bacteria and actinomycetes showed the reverse trend. Bacteria to fungi (B/F) ratio increased from 222.30 at the end of the first crop to 667.16 at the end of the second crop. The contents of biocontrol agents, Purpureocillium lilacinum and Bacillus subtilis, remained stable in soils under continuously cropped cucumber. Although insignificantly, the amount of pathogen Fusarium oxysporum f. sp. cucumerinum decreased. On the other hand, soil bacteria diversity significantly increased. This somehow promoted beneficial bacteria TRF139 propagation while inhibiting harmful bacteria TRF341 and TRF501. Moreover, the technique improved cucumber yield by 25.9% under continuous cropping and reduced root-knot nema-tode disease index by 71.4% at the end of the third crop. Thus the combination of corn stalk and biocontrol agents positively influenced soil microbes and their community structures, promoted biocontrol agent colonization within a few crops, inhibited the growth of pathogens and subsequently improved the health of soil microenvironment.