西瓜连作对土壤主要微生物类群和土壤酶活性的影响

从昌乐不同种植年限西瓜大棚采集土壤,测定了连续种植6、8、10、14和20年西瓜大棚土壤中细菌、放线菌和真菌数量、土壤酶活性及土壤理化特性状的变化特点.结果表明:随着种植年限的增加,土壤中细菌、放线菌呈现先升后降趋势;真菌数量变化趋势则与之相反;蛋白酶、多酚氧化酶也同样呈现先升后降趋势,脲酶呈下降趋势,蔗糖酶呈上升趋势;同时在连作栽培过程中,土壤中速效氮含量较为稳定,速效钾和速效磷的含量随着连作年限的增加出现少量积累,土壤酸化日趋严重.讨论了连作条件下土壤微生物数量与土壤酶活性及土壤理化性状之间的关系.

Effects of Watermelon Replanting on Main Microflora of Rhizosphere and Activities of Soil Enzymes

Soil samples collected from greenhouses with 6, 8, 10, 14 and 20 years watermelon replanting, respectively, in Changle, Shandong province were analyzed for number of bacteria, actinomycetes, and fungi, and soil enzyme activities, and pH, N, P, K, and organic matter contents in soil. Results showed that with year increasing of replanting, the number of bacteria and actinomycete showed a trend of increasing first and then decreasing afterward; the activities of proteinase and polyphenoloxidase had a similar trend as those of the number of bacteria and actinomycete; however, the trend of the number of fungi was totally opposite to that. As the replanting year increasing, the urease activity decreased, while the saccharase activity increased. Results also showed that the nitrogen content of replanting soil was not evidently changed, while the contents of P, K in the soil had a little accumulation after replant of watermelon. The relationship between microflora, soil enzyme activities, physical and chemical character in replanting soils was also discussed.