日光温室连作黄瓜根际微生物区系的变化

目的]研究黄瓜再植病害的发生机理。方法]选择种植年限分别为13、、5、7和8年的日光温室,采集0~20 cm根区耕层土壤,测定微生物类群和数量。结果]连续种植5年的土壤中微生物数量最多,达2.2×108cfu/g（干土）;8年的最少,为2.7×107cfu/g（干土）。细菌占微生物总量的97%以上。随连作年限的增加,细菌和放线菌数量表现出先增加后减少的趋势,第5年达到最大值,分别为2.17×108和1.92×106cfu/g（干土）;真菌数量随连作年限的增加呈增长趋势。随连作年限的增加,氨化细菌、固氮菌和纤维素分解菌数量呈现先增加后降低的趋势,分别在连作5、3和3年达到最大值,而硝化细菌数量随连作年限的增加急剧下降。结论]黄瓜连作显著地改变了根际微生物区系。

Variation of Microflora in Cucumber Rhizosphere of Continuous Cropping in Greenhouse

Objective] The aim was to study the occurrence mechanism of cucumber replant disease.Method] The greenhouses with planting years of 1,3,5,7 and 8 were selected and the tilling layer soil in root zone of 0-20 cm was collected to determine the microbial group and quantity.Result] The microbe quantity in the soil continuously cropping for 5 yr was the most,reaching 2.2×108 cfu/g dry soil and that in soil for 8 yr was least,being 2.7×107 cfu/g dry soil.The bacteria accounted for more than 97% of total microbe number.With the increase of continuous cropping year,the quantity of bacteria and actinomycetes showed the tread of first increase and then decrease and reached the biggest value at 5 yr,being 2.17×108 and 1.92×106 cfu/g dry soil resp.The fungi quantity showed the increasing tread with the increase of continuous cropping year.With the increase of continuous cropping year,ammonifying bacteria,azotobacter and cellulolytic bacteria showed the tread of first increases and then decreases and reached the biggest value at continuous cropping for 5 and 3 yr,while the nitrifying bacteria quantity was decreased sharply with the increase of continuous cropping year.Conclusion] Continuous cropping cucumber obviously changed the microflora in rhizosphere.