Root-associated microbiomes of wheat under the combined effect of plant development and nitrogen fertilization

ROC levels varied dramatically across wheat growth stages and correlated more with the bacterial community than with the fungal community. Rhizosphere SOC and SAC levels were elevated by long-term N fertilization but varied only slightly across growth stages. Variation in the microbial community structure across plant growth stages showed a decreasing trend with N fertilization level in the rhizosphere. In addition, more bacterial and fungal genera were significantly correlated in the jointing and ripening stages than in the tillering stage in the root samples. A number of bacterial genera that shifted in response to N fertilization, including Arthrobacter, Bacillus and Devosia, correlated significantly with acetic acid, oxalic acid, succinic acid and tartaric acid levels.

根系有机碳（Root Organic Carbon, ROC）水平在小麦不同生育期差异显著，且与细菌群落的相关性高于真菌群落。根际土壤有机碳（Soil Organic Carbon, SOC）与根际有效碳（Soil Available Carbon, SAC）水平经长期施氮肥处理后显著升高，但在不同生育期仅存在小幅波动。根际土壤中，微生物群落结构随小麦生育期的变异程度随施氮水平升高呈下降趋势。此外，根系样本中，拔节期与成熟期的显著相关细菌属与真菌属数量均多于分蘖期。响应氮肥施用发生丰度偏移的多个细菌属，包括节杆菌属（Arthrobacter）、芽孢杆菌属（Bacillus）与德沃斯氏菌属（Devosia），均与乙酸、草酸、琥珀酸及酒石酸水平呈显著相关。