The abundant and rare populations of microorganisms in the ecosystem play a crucial role in preventing pathogen transmission, regulating nutrient cycling, facilitating pollutant degradation. However, less attention has pain on the agroecosystems. We conducted a field experiment to evaluate the effects of different potassium application rates (0, 75, 150, 225, 300 kg·hm-2) on the microbial diversity, the driving factors and the microbial community assembly process of the sugarcane rhizosphere through the high-throughput sequencing and ecological mode-ling techniques. The results showed that the potassium application exerted a significant effect on soil nutrient content and soil enzyme activities, which were highest at the application rate of 300 and 225 kg·hm-2, respectively. The abundant populations mainly concentrated in a few dominant species. Potassium application significantly affected species composition and community structures of the rhizosphere microorganisms. Under potassium application, soil urease, soil organic matter, and catalase were the key limiting factors, which could affect community structures of the abundant and rare microbial populations. The effects of potassium application on the rhizosphere bacterial community were greater than those on the fungal community, and the effects on the abundant microbial community was greater than that on the rare one. Community assembly of bacteria and fungi were predominantly driven by determini-stic processes in the sugarcane rhizosphere, with the heterogeneity selection dominating in bacteria and the homogeneity selection dominating in fungi. The deterministic processes played a key role in the abundant and rare communities assembly. In conclusion, our results demonstrated that potassium application significantly affected soil nutrients and enzyme activities. The potassium application could enhance the diversity of abundant and rare populations of bacteria and fungi and regulate soil microbial community assembly in the rhizosphere.
微生物丰富种群和稀有种群在生态系统中发挥着防止病原体传播、控制养分循环和促进污染物降解等关键作用,但目前在农田生态系统中关注较少。本研究使用高通量测序技术和构建生态模型系统评估了不同施钾量(0、75、150、225和300 kg·hm-2)对甘蔗根际土壤细菌和真菌的丰富种群及稀有种群多样性、驱动因素和群落构建过程的影响。结果表明: 施钾肥能够显著改变甘蔗土壤养分含量和酶活性特征,在施钾量为300和225 kg·hm-2时土壤养分含量和酶活性分别达到最高。甘蔗根际土壤微生物的丰富种群集中在几个优势类群中,施钾肥能够极显著改变根际微生物物种组成和群落结构。施钾肥条件下土壤脲酶、有机质和过氧化氢酶等是影响细菌和真菌丰富种群与稀有种群群落结构的主要限制性因子。同时施钾肥对根际细菌群落的影响大于真菌,对丰富种群的影响大于稀有种群。施钾肥后甘蔗根际细菌和真菌群落构建过程主要由确定性过程驱动,细菌群落中异质选择占主导过程,而真菌群落中同质选择占主导过程,同时细菌和真菌丰富种群和稀有种群的群落构建也受确定性过程驱动。综上表明,施钾对甘蔗土壤养分和酶活性存在显著影响,增施钾肥有助于增加细菌和真菌丰富种群及稀有种群的多样性,调控甘蔗根际土壤微生物群落构建过程。.
Keywords: sugarcane; potassium fertilizer; rhizosphere microbial community; abundant microbial community; rare microbial community; community assembly; soil enzyme activity.