Wheat seedlings are significantly impacted by the presence of bacteria. However, bacteria are unavoidably growing together with wheat. The study aimed to reveal wheat photosynthesis, phyllosphere bacterial community composition, and a shift in the bacterial community following different density treatments in a closed artificial ecosystem. Here, we report the relationship between photosynthesis and bacterial community in wheat seedlings for different planting densities. In this closed artificial ecosystem, a total of 30 phyla were detected, with 17 of them were simultaneously present in four treatments, under high light intensity and carbon dioxide growth environment. The key phyla detected include Firmicutes, Proteobacteria, and Bacteroidetes. We found that planting densities significantly impacted the photosynthetic characteristics of wheat and bacterial genetic biodiversity, but not on species composition of the bacterial community. Network analysis shows that the phyllosphere bacteria network structures were characterized by the clustering coefficient and modularity. Network for the 1000 plants/m² treatment group exhibits the highest levels of average clustering coefficient but lowest modularity and number of modules, among all plant densities tested. In addition, the network for the 1200 plants/m² treatment group exhibits the best characteristics in terms of net photosynthesis rate and intrinsic water use efficiency, higher complex phyllosphere community network structures, higher abundance of Corynebacterium, and more function of “Amino acid metabolism”, which encourages the plants to grow better. The findings presented in this work elucidated the role of plant density in the growth of phyllosphere bacteria during wheat seedlings and provided theoretical support for reasonable wheat density cultivation in closed artificial ecosystems and wheat field production.

细菌的存在会严重影响小麦幼苗。然而，细菌不可避免地与小麦一起生长。这项研究旨在揭示小麦在封闭的人工生态系统中进行不同密度处理后的光合作用，叶环细菌群落组成以及细菌群落的变化。在这里，我们报告了不同种植密度下小麦幼苗光合作用与细菌群落之间的关系。在这个封闭的人工生态系统中，在高光照强度和二氧化碳生长环境下，共检测到30种门，其中四种处理同时存在17种。检测到的主要门系包括Firmicutes，Proteobacteria和Bacteroidetes。我们发现种植密度显着影响小麦的光合特性和细菌遗传生物多样性，但不影响细菌群落的物种组成。网络分析表明，叶球细菌网络结构具有聚类系数和模块化特征。在所有测试的植物密度中，用于1000个植物/ m ²处理组的网络显示出最高水平的平均聚类系数，但模块性和模块数量最低。此外，在净光合速率和内在水分利用效率，较高的复杂叶圈社区网络结构，较高的丰度方面，用于1200株/ m ²处理组的网络表现出最佳的特性。棒杆菌，还有更多的“氨基酸代谢”功能，可以鼓励植物更好地生长。这项工作中提出的发现阐明了植物密度在小麦幼苗期间叶际细菌生长中的作用，并为在封闭的人工生态系统中合理的小麦密度栽培和麦田生产提供了理论支持。