The usage of fertilizer with high nitrogen content in many countries, as well as its enormous surplus, has a negative impact on the soil ecological environment in agricultural system. This consumption of nitrogen fertilizer can be minimized by applying biochar to maintain the sufficient supply of nitrogen as nutrient to the near-root zone. This study investigated the effects of various amounts of biochar application (450, 900, 1350, and 1800 kg/hm2) and reduction of nitrogen fertilizer amount (10, 15, 20, and 25%) on the nutrients and microorganism community structure in rhizosphere growing tobacco plant. The microorganism community was found essential in improving nitrogen retention. Compared with conventional treatment, an application of biochar in rhizosphere soil increased the content of soil available phosphorus, organic matter and total nitrogen by 21.47%, 26.34%, and 9.52%, respectively. It also increased the abundance of microorganisms that are capable of degrading and utilizing organic matter and cellulose, such as Actinobacteria and Acidobacteria. The relative abundance of Chloroflexi was also increased by 49.67-78.61%, and the Acidobacteria increased by 14.79-39.13%. Overall, the application of biochar with reduced nitrogen fertilizer amount can regulate the rhizosphere microecological environment of tobacco plants and their microbial population structure, thereby promoting soil health for tobacco plant growth while reducing soil acidification and environmental pollution caused by excessive nitrogen fertilizer.

烟草青枯病是一种细菌性病害,对烟株生长危害严重,为探究烟株发病后土壤微生物群落结构变化及其生物学调控机制,采用大田试验方法,设置ZCTR(常规施肥,健康烟株的根际土壤)、ZCSW(施加1.2 t·hm-2生物炭,健康烟株的根际土壤)、QKTR(常规施肥,青枯病烟株的根际土壤)和QKSW(施加1.2 t·hm-2生物炭,青枯病烟株的根际土壤)4个处理,研究细菌群落结构的差异.结果 表明,生物炭施用后细菌α多样性升高,但差异不显著,细菌群落丰富度和菌群结构均有所改变.相同施肥条件下,青枯病烟株的根际土壤细菌α多样性和群落丰富度均小于健康烟株根际土壤;未添加生物炭的青枯病烟株根际土壤与健康烟株根际土壤相比,芽单胞菌门、酸杆菌门的丰度增加0.26、1.27个百分点,变形菌门、放线菌门的丰度降低1.08、0.14个百分点.施用生物炭后烟株的株高、叶长、叶宽、茎围分别较未添加生物炭处理增加了11.83％、16.88％、6.70％、10.80％,同时降低了烟株的病害指数,施加生物炭处理青枯病的发病率较未施加生物炭处理低9.1个百分点.研究表明,生物炭的施用会缓解青枯病带来的细菌丰富度下降,减少致病性细菌门类的相对丰度,并驱动功能促生性细菌(芽单胞菌门)相对丰度增加,从而降低青枯病发病率.研究初步明确了生物炭对植烟土壤青枯病微生态调控的作用机制.

[目的]探明硝态氮与铵态氮配比对烤烟生长及烟叶产质量的影响,为南平烟区烤烟施肥提供科学依据.[方法]采用大田试验方法,研究硝态氮与铵态氮不同配比烤烟大田生育期、农艺性状及烟叶化学成分含量与经济性状的变化.[结果]硝态氮与铵态氮不同配比对烤烟大田生育期的影响不明显,团棵期前铵态氮有利于烤烟的生长及烟叶的开面,进入旺长期后提升硝态氮比例的烟株粗壮,叶片数较多,有利于烤烟的生长;不同配比处理烟叶总糖和还原糖均偏低,烟碱含量偏高,糖碱比失衡,氮碱比均较适宜;大田烤烟赤星病和气候斑点病的发病率和病情指数分别为9.16％～12.48％、1.88～3.57和1.85％～8.10％、0.52～2.57,增加硝态氮比例有利于提高烤烟对赤星病的抗性,增加铵态氮比例烤烟气候性斑点病的发生率降低,普通花叶病零星发生且发病较轻;不同配比处理烤后烟叶的产量、产值、均价、上等烟比例和中等烟比例分别为 175.15～181.51 kg/667m2、4 191.10～4 487.26元/667m2、23.91～24.72元/kg、49.89％～56.35％和43.65％～49.44％,差异均不显著.[结论]硝态氮:铵态氮为5 ∶ 5时,烤烟的农艺性状及烤后烟叶的化学成分含量与经济性状等综合表现最好.