| 稻田与旱地土壤中真菌和细菌对秸秆碳的利用特征 |
| 摘要点击 2585 全文点击 596 投稿时间：2021-07-18 修订日期：2021-07-29 |
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| 中文关键词 磷脂脂肪酸 真菌 细菌 稻田 旱地 矿化 |
| 英文关键词 13C phospholipid fatty acid analysis fungi bacteria paddy upland mineralization |
| 作者 | 单位 | E-mail | | 邓少虹 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125
中国科学院大学, 北京 100049 | dengshaohong18@mails.ucas.ac.cn | | 郑小东 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125
广东省农业科学院农业资源与环境研究所, 广州 510640 | | | 毛婉琼 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125
中国科学院大学, 北京 100049 | | | 陈香碧 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | xbchen@isa.ac.cn | | 胡亚军 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | | | 程爱武 | 湖南省宁乡市农业技术推广中心, 宁乡 410600 | | | 何寻阳 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | | | 苏以荣 | 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 | yrsu@isa.ac.cn |
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| 中文摘要 |
| 微生物将植物残体矿化为CO2和同化为微生物细胞组成部分是新鲜有机物料转化为土壤有机质的关键环节.以亚热带两种典型农业利用（稻田和旱地）土壤为对象，采用40 d室内模拟培养试验结合磷脂脂肪酸-稳定同位素示踪联用（13C-PLFA-SIP）技术，研究13C标记秸秆的矿化特征以及参与秸秆降解的细菌和真菌类群变化规律.结果表明，培养前期（0.25~1 d），秸秆碳在稻田土壤中的矿化速率高于旱地土壤，中期（2~20 d）以稻田土壤低于旱地土壤（P<0.05），后期（21~40 d）两者矿化速率相当.培养结束时，秸秆碳在稻田土壤中的累积矿化率（11%）约为旱地（20%）的一半.尽管稻田土壤中总微生物量（PLFA总量）比旱地高，但两种土壤中秸秆碳被微生物同化为细胞组分的量（13C-PLFA）相当，且稻田中秸秆碳的富集比例（PLFA中13C占总碳量的百分比）低于旱地，说明稻田土壤中参与秸秆碳降解的活性微生物占比少.整个培养期内，稻田土壤中秸秆碳被微生物利用的优势类群为细菌（占13C-PLFA总量的比例最高达86%，其中革兰氏阳性菌59%、革兰氏阴性菌27%），旱地土壤则主要为真菌（最高占比达75%）.这主要是由于稻田淹水环境抑制了微生物活性，且对好氧微生物（真菌）的抑制作用强于细菌.基于细菌和真菌生存策略及其残留物周转特征，结果表明稻田和旱地环境条件下利用碳源底物的优势微生物类群差异可能是导致两种土壤中微生物源有机碳积累和稳定性差异的主因. |
| 英文摘要 |
| Two typical subtropical agricultural soils, a flooded paddy soil and its adjacent upland, were collected and then incubated with or without 13C-labeled crop residue (maize straw) for 40 days. During the incubation, the mineralization rate of the crop residue was monitored, and the 13C incorporated into fungal and bacterial phospholipid fatty acid (PLFA) was quantified. At the early stage (0.25-1 days), the mineralization rate of crop residue was faster in paddy soil than that in upland soil, whereas the opposite trend was observed from 2 to 20 days. At the late stage (21-40 days), the mineralization rate was similar in both soils. At the end of incubation, 11% of the total crop residue was mineralized in paddy soil, which was about half of that in upland soil (20%). Although paddy soil had a higher amount of microbial biomass (indicated by total PLFA), the total amounts of 13C-PLFA were comparable in both soils, and the enrichment ratio (proportion of 13C to total C in PLFA) was lower in paddy soil than that in upland soil. This indicated that the microbial community in paddy soil was less active in the uptake of crop residue C than that in upland soil. During the incubation, the residue-derived 13C was mainly distributed in bacterial PLFA (up to 86% of total 13C-PLFA, including 59% in gram-positive and 27% in gram-negative bacteria) in paddy soil, and up to 75% of total 13C-PLFA distributed in fungal PLFAs was in upland soil. Thus, bacteria dominated the utilization of crop residue in paddy soil versus fungi in upland soil. Compared with that in upland soil, the microbial activity was suppressed in the anaerobic condition caused by flooding in paddy soil, with a stronger inhibition of fungi than bacteria. Considering the discrepancies of life strategies and necromass turnover between bacteria and fungi, the different dominant microbial groups in the utilization of crop residue in water-logged and well-drained conditions could lead to the distinct accumulation and stabilization of microbial-derived organic matter in paddy and upland soils. |
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