海南岛不同撂荒年限的热带农田土壤固碳细菌群落特征.

【Objective】The paper aimed to explore the impact of different years of abandonment in tropical regions on soil carbon fixing bacterial communities in farmland, and provide theoretical basis and data support for sustainable agricultural management. 【Method】Real time quantitative PCR and high-throughput sequencing technology were used to analyze the gene abundance, community diversity, and differences of soil carbon fixing bacteria in farmland, short-term abandoned land (2＜abandoned years＜5), and long-term abandoned land (abandoned years＞5) in the central region of Hainan Island. 【Result】The abundance of cbbL gene in the soil within the region ranged from 3.11×107-2.84×108 copies/g of dry soil, showing a trend of farmland＞short-term abandoned land＞long-term abandoned land. Compared with the control farmland, long-term abandoned land reduced the Chao1 index, Observed Specifications index and Shannon index of soil carbon fixing bacteria. The dominant phyla of carbon fixing bacteria in tropical farmland soils with different abandonment years were Pseudomonadota and Actinomycetota, and the dominant genera were Bradyrhizobium, Mycobacterium, Rhodopseudomonas, Rubrivivax, Blastochlolis, Nocardia, Mesorhizobium, Dokdonella and Azospirillum, and most of them were facultative autotrophic bacteria. The overall changes in the community structure of soil carbon fixing bacteria with different abandonment years showed clustering according to each abandonment year. A total of 33 differential markers were analyzed for three different abandonment years of soil, including 17 in farmland, 5 in short-term abandonment land, and 11 in long-term abandonment land. The RDA results showed that the community structure of soil carbon fixing bacteria was significantly influenced by SOC, SWC, ROC, TP, TN, Coarse sand, pH and Fine sand. 【Conclusion】The increase in abandoned years has reduced the gene abundance of soil carbon fixing bacteria, and the community structure has also changed. Environmental factors such as SOC, SWC, ROC, TP and TN have a significant impact on the community structure of soil carbon fixing bacteria. [ABSTRACT FROM AUTHOR]