水分条件对水稻土微生物群落多样性及活性的影响

采用BIOLOG碳素利用法、磷脂脂肪酸（PLFA）法和土壤酶活性测定等方法比较了三种水分条件（淹育、淹育晾干、非淹育）对水稻土微生物群落多样性及活性的影响。结果表明，淹育处理水稻土的脱氢酶、蔗糖酶活性明显高于淹育晾干和非淹育处理，并导致该土壤的基础呼吸升高。BIOLOG碳素利用法表明，非淹育处理的微生物群落平均吸光值（AWCD）显著低于淹育和淹育晾干处理。磷脂脂肪酸（PLFA）实验发现，淹育水稻土的真菌特征脂肪酸（18：2w6，9c）所占比例减少，真菌特征脂肪酸（18：2w6，9c）与细菌特征脂肪酸（15：0i＋15：0a＋16：0i＋16：1w5c＋17：0i＋17：0a＋17：0cy＋17：0＋18：1w7c＋19：0cy）的比值下降；水分条件变化没有改变土壤微生物环丙基脂肪酸19：0cy的相对丰度，但非淹育处理的环丙基脂肪酸17：0cy相对丰度明显高于另外二种处理。BIOLOG碳素利用法的群落水平生理剖面（CLPP）和磷脂脂肪酸（PLFA）测定结果经聚类分析后，发现淹育和淹育晾干处理的土壤微生物多样性在较低的距离尺度可聚成一类，且与非淹育土壤具有明显差异。淹育水稻土与淹育晾干相比，尽管土壤微生物群落结构和功能多样性有一定的相似性，但微生物的种群组成和活性仍发生了较大的变化。

INFLUENCE OF SOIL MOISTURE REGIME ON MICROBIAL COMMUNITY DIVERSITY AND ACTIVITY IN A PADDY SOIL

Influence of soil moisture regime (non-flooding,flooding-drying,and flooding) on microbial community diversity and activity was investigated by determining Biolog sole carbon source utilization pattern,phospholipid fatty acid (PLFA) profiles and enzyme activity indices.Increased dehydrogenase and invertase activities were observed in Treatment Flooding as compared to what in the other two treatments,which apparently led to enhanced soil basal respiration.The average well colour development (AWCD) of the carbon sources on Biolog plates was significantly lower in Treatment Non-flooding than in the other two treatments.The fungal indicator (18:2w6,9c) and the proportion of fungal biomarker (18:2w6,9c) to bacterial biomarkers (15:0i+15:0a+16:0i+16:1w5c+17:0i+17:0a+17:0cy+17:0+18:1w7c+19:0cy) were lower under flooding conditions.The relative abundance of cyclopropyl fatty acid 19:0cy was not affected by moisture regime,however,the relative abundance of 17:0cy was the highest in Treatment Non-flooding.Cluster analyses of the sole carbon source utilization and PLFA data demonstrated that Treatment Non-flooding differed from the other two treatments in soil microbial community.Although certain similarity was found between Treatment Flooding and Treatment Flooding-drying in structure and functional diversity of soil microbial community,the findings of the study suggested that there were some drastic changes in microbial community composition and activity associated with variation of soil moisture regime.