黑土固氮菌功能多样性及对玉米的减氮促生作用

Nitrogen-fixing bacteria from black soil with functional diversity promote maize growth with reduced fertilizer use

摘要:

氮肥是农业种植的重要化学肥料，也是作物增产的关键肥力因素，然而土壤中氮肥缺乏或过量施用会引起农田土壤酸化、板结和作物减产等一系列问题。固氮菌通过固氮酶将空气中的氮还原为作物可吸收的氨，进而提高土壤质量并促进作物生长。目的 从东北黑土中筛选固氮菌资源，探究其对黑土质量提升和玉米生长的促进作用，为开发适配东北黑土环境的微生物菌剂提供优质菌种资源。方法 采用微生物分离培养与功能表征技术测定所获固氮菌的固氮、解磷及吲哚-3-乙酸分泌能力；通过玉米盆栽试验及土壤理化性质分析评价固氮菌对土壤质量和玉米生长的影响。结果 从东北黑土中获得3株固氮菌，其中类芽孢杆菌(Paenibacillus sp.) AHC-20固氮能力较强；拉乌尔菌(Raoultella sp.) Z93和副伯克霍尔德菌(Paraburkholderia sp.) W22为多功能菌株，兼具固氮、解磷和吲哚-3-乙酸生成能力。将这3株固氮菌施用于玉米黑土盆栽，减施化肥并施加固氮菌AHC-20的处理组的玉米株高、生物量和叶绿素含量均显著高于全肥对照组；黑土中无机碳、有机碳、有机质、铵态氮和硝态氮含量明显增加，表明高效固氮菌AHC-20在玉米减肥促生和黑土肥力提升方面效果良好。结论 黑土固氮菌能有效促进玉米生长并改善黑土质量，实现“减肥不减产”，具有良好的固氮微生物菌剂开发潜力。

Abstract:

Nitrogen fertilizer is an important chemical fertilizer for agricultural planting and an important fertility factor for increasing crop yields. Lack or excess of nitrogen fertilizer in soil will lead to soil acidification, soil consolidation, low crop yields and so on. Nitrogen-fixing bacteria can reduce nitrogen in the air to ammonia that is beneficial to crops through the action of nitrogenase. This process helps improve soil quality and subsequently promote crop growth.Objective To obtain nitrogen-fixing bacteria from the black soil of northeast China and explore the effects of nitrogen-fixing bacteria on soil quality and maize growth, thus providing excellent strain sources for the development of microbial agents suitable for the environment of black soil in northeast China.Methods We employed microbial isolation, culture, and functional characterization to measure the nitrogen fixation, phosphorus solubilization, and indole-3-acetic acid (IAA) secretion of the screened nitrogen-fixing bacteria. Pot experiments and soil physical and chemical tests were carried out to evaluate the effects of nitrogen-fixing bacteria on soil quality and maize growth.Results Three strains of nitrogen-fixing bacteria were obtained from the black soil of northeast China. Among them, Paenibacillus sp. AHC-20 had higher nitrogen-fixing ability, while Raoultella sp. Z93 and Paraburkholderia sp. W22 were multifunctional strains capable of fixing nitrogen, solubilizing phosphorus, and producing IAA at the same time. The three nitrogen-fixing strains were then applied to the black soil planted with maize. The plant height, biomass, and chlorophyll content of maize significantly increased in the chemical fertilizer reduction+AHC-20 group compared with those in the control group with application of only chemical fertilizer. In addition, the content of inorganic carbon, organic carbon, organic matter, ammonium nitrogen, and nitrate nitrogen in black soil also increased significantly, which indicated that the efficient nitrogen-fixing bacterial strain AHC-20 promoted maize growth upon chemical fertilizer reduction and improved the fertility of black soil.Conclusion Nitrogen-fixing bacteria in black soil can effectively promote the growth of maize and improve the quality of black soil to achieve fertilizer reduction without compromising crop yields, showing the potential for the development of nitrogen-fixing microbial agents.