林刚云 肖健 吴银秀 黄小丹 杨尚东 屈达才

摘要：【目的】分析秸稈覆盖还田对桑园土壤肥力及其细菌多样性的影响，阐明秸秆覆盖还田技术对南方桑园土壤肥力及健康的影响机制与应用前景，为构建稳定高产、可持续发展的桑树栽培管理体系提供参考依据。【方法】设秸秆覆盖还田桑园和对照桑园（非秸秆覆盖还田桑园）2个处理，其中，秸秆覆盖还田处理是将水稻秸秆切碎、自然堆沤50～60 d后覆盖于桑树根系两旁，覆盖45 d后分别采集秸秆覆盖还田桑园和对照桑园的土壤样品，利用传统的测定方法和Illumina高通量测序技术分析秸秆覆盖还田对桑园土壤生物学性状及土壤细菌群落结构特征的影响。【结果】秸秆覆盖还田桑园土壤β-葡糖苷酶、氨肽酶和磷酸酶活性及土壤微生物生物量碳（MBC）、微生物生物量氮（MBN）和微生物生物量磷（MBP）含量均显著高于对照桑园土壤（P<0.05，下同）;秸秆覆盖还田桑园土壤的菌群Chao1和Shannon指数也显著高于对照桑园土壤。在秸秆覆盖还田桑园和对照桑园土壤中相对丰度大于1.00%的优势细菌门分类数量均为11个，但二者的优势细菌门分类组成比例存在一定差异;相对于对照桑园土壤，秸秆覆盖还田桑园土壤中Bacteroidota的相对丰度急剧增加，而绿弯菌门（Chloroflexi）和Verrucomicrobiota的相对丰度急剧下降。在秸秆覆盖还田桑园和对照桑园土壤中相对丰度大于1.00%的优势细菌属分类数量分别为23和24个;与对照桑园土壤相比，秸秆覆盖还田桑园土壤中虽然慢生根瘤菌属（Bradyrhizobium）、假双头斧形菌属（Pseudolabrys）、Dongia、Candidatus_Udaeobacter和norank_f_JG30-KF-AS9等优势细菌属部分缺失，但富集了类诺卡氏菌属（Nocardioides）、norank_f_Methyloligellaceae、黄杆菌属（Flavobacterium）和微枝形杆菌属（Microvirga）等特有优势菌属。秸秆覆盖还田桑园土壤的特有细菌属为199个、特有细菌种为390个，分别是对照桑园土壤特有细菌属和细菌种的3.75和2.52倍。【结论】秸秆覆盖还田不仅显著提高桑园土壤肥力，还改变桑园土壤优势细菌不同（门、属）分类水平的组成比例，形成更丰富多样的土壤细菌群落结构，而有助于维护桑园土壤健康。

关键词： 秸秆覆盖还田;桑园;土壤酶活性;土壤微生物生物量;细菌群落结构

中图分类号： S154.36                          文献标志码： A 文章编号：2095-1191（2020）10-2339-09

Effects of straw mulching on soil biological properties and bacterial community structure in mulberry plantation

LIN Gang-yun， XIAO Jian， WU Yin-xiu， HUANG Xiao-dan，

YANG Shang-dong， QU Da-cai*

（College of Agriculture， Guangxi University， Nanning  530004， China）

Abstract：【Objective】Analyzing the effects of straw mulching on soil fertility and bacterial diversity in mulberry fields， and clarifying the mechanism and application prospects for straw mulching techniques on soil fertility and health in sou-thern mulberry fields， in order to provide a reference basis for building a stable， high-yield and sustainable mulberry cultivation system. 【Method】Two treatments were set up， including straw mulching and returning to the mulberry field and the control mulberry field（non straw mulching and returning field）. The straw mulching treatment was to cut the rice straw to pieces， pile it up naturally for 50-60 d and then cover both sides with the mulberry root system， and collect the straw mulch after 45 d of covering. The soil samples of returning mulberry fields and control mulberry fields were used to analyze the effects of straw mulching on soil biological properties and soil bacterial community structure characteristics using traditional measurement methods and Illumina high-throughput sequence technology. 【Result】The activities of β-glucosidase， amino peptidase and phosphate in mulc-hing soils of mulberry plantation were all significantly higher than those of control（P<0.05， the same below）， as well as the microbial biomass carbon（MBC）， microbial biomass nitrogen（MBN）， microbial biomass phosphorus（MBP）. The Chao1 and Shannon indexes of the microbial community of the mulberry soil covered with straws were also significantly higher than those of the control mulberry soil. In both straw mulching mulberry fields and control mulberry fields， there were 11 types of dominant bacteria whose relative abundance was greater than 1.00%， but there were some differences in the composition ratio of dominant bacteria. In addition， compared to the control mulberry soil， the ratios of Bacteroidota increased sharply and Chloroflexi， Verrucomicobiota decreased sharply in mulching soils of mulberry plantation at phylum level. There were 23 and 24 dominant bacterial genera in the soil with relative abundance greater than 1.00% in straw mulching mulberry fields and control mulberry fields， respectively. Moreover， some dominant bacteria， such as Bradyrhizobium，Pseudolabrys，Dongia，Candidatus_Udaeobacter and norank_ f_JG30-KF-AS9 even though lost in mulching soil of mulberry plantation， but Nocardioides，norank_f_Methyloligellaceae，Flavobacterium and Microvirga accumulated in mulching soil as its unique dominant bacteria. There were 199 unique bacteria genera and 390 unique bacteria species in the soil of straw mulching mulberry field， which were 3.75 times and 2.52 times of those in the soil of control mulberry field. 【Conclusion】Straw mulching not only can significantly improve soil fertility， but also change the proportions of soil dominant bacterial community structure（phylum and genus）， and form a more diverse soil bacterial community structure. It is helpful for maintaining the health of mulberry field soil.

Key words： straw mulching and returning to field; mulberry field; soil enzyme activity; soil microbial biomass; bacterial community structure

Foundation item： Special Project for Guangxi Innovation Team Construction of National Modern Agricultural Industrial Technology System（nycytxgxcxtd-02-04）; University Science and Technology Innovation and Service Capacity Enhancement Project of Guangxi（Guijiaokeyan〔2020〕8）

0 引言

【研究意義】桑树（Morus alba L.）是我国重要的多年生木本经济植物。据统计，我国现有的桑树种质资源居世界第一，约3000份，分属15个种和4个变种（苏超和焦锋，2011;杜伟等，2017）。广西是我国最大的桑蚕生产基地，无论是桑园面积还是蚕茧产量均连续多年位居全国首位，2018、2019年广西桑园面积分别为22.85万和19.72万ha，蚕茧产量分别达40.44万和37.4万t（林强，2020;张志林等，2020）。但目前广西桑园管理偏施氮肥，普遍存在氮、磷、钾肥施用比例失调等问题，造成土壤肥力下降进而导致桑叶产量降低，严重制约了广西桑蚕产业的健康发展（张志林等，2020）。……