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Article|19 Feb 2022|OPEN
Tea plant–legume intercropping simultaneously improves soil fertility and tea quality by changing Bacillus species composition
Zhi Huang1 ,† , Chunhong Cui2 ,† , Yajun Cao1 ,† , Jinghui Dai1 , Xiaoyue Cheng1 , Shaowei Hua1 , Wentao Wang1 , Yu Duan3 , Evangelos Petropoulos4 , Hui Wang1 , Lixiang Zhou2 , Wanping Fang3 , and Zengtao Zhong,1 ,
1College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
2College of Resource and Environment Sciences, Nanjing Agricultural University, Nanjing 210095, China
3College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
4School of Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
*Corresponding author. E-mail: fangwp@njau.edu.cn,ztzhong@njau.edu.cn
Zhi Huang,Chunhong Cui and Yajun Cao contributed equally to the study.

Horticulture Research 9,
Article number: uhac046 (2022)
doi: https://doi.org/10.1093/hr/uhac046
Views: 172

Received: 28 Sep 2021
Accepted: 22 Jan 2022
Published online: 19 Feb 2022

Abstract

The tea plant is an economically important crop in China, but long-term monoculture and substantial chemical nitrogen fertilizer input cause soil acidification, which in turn affects the nutrient supply and tea quality. Intercropping has drawn more attention in tea gardens because this pattern is expected to improve soil fertility and tea quality and change the soil microbial community composition. However, the roles of some key microorganisms in rhizosphere soils have not been well characterized. Here, a “soybean in summer and smooth vetch in winter” strategy was used in a tea garden to investigate the effects of intercropped legumes on soil fertility, tea quality, and potential changes in beneficial bacteria such as Bacillus. Our data showed that when soybeans were turned into the soil, the intercropping system exhibited higher soil organic matter (SOM), total nitrogen (TN), tea quality indices, and expression of the Camellia sinensis glutamine synthetase gene (CsGS). Notably, intercropping significantly affected the bacterial communities, decreasing the relative abundance of Bacillus but increasing its absolute abundance. Bacillus amyloliquefaciens BM1 was isolated from intercropped soil and showed outstanding plant growth-promoting (PGP) properties when co-inoculated with rhizobia. In winter, intercropping with smooth vetch had a beneficial effect on soil properties and tea quality. Co-inoculation with strain BM1 and Rhizobium leguminosarum Vic5 on smooth vetch (Vicia villosa) produced huge improvements in SOM, TN, and tea leaf quality, which were accompanied by the highest level of amino acids and the lowest levels of polyphenols and caffeine (p < 0.05). Our findings demonstrate that intercropping with some legumes in the tea garden is a strategy that increases SOM, TN, and tea quality, and the optional use of some PGP Bacillus species produces an amplification effect.