钾对烟草根际氮细菌、氮古菌群落及氮代谢的影响

摘要

为提高烟草栽培品质,采用高通量测序技术和分光光度法探讨了不同施钾水平对根际氮细菌、氮古菌和氮代谢的影响.结果表明:旺长期,烟草根际反硝化作用菌和硝酸还原菌与施钾水平呈负相关,且当N:K2O=1:2.1时,氮素有效性较高,相比对照提高了20.9%,利于烟草生长.晚成熟的上部叶总氮、烟碱含量升高,糖含量降低,烟叶质量受到影响,但在N:K2O=1:3.5~4.2时总氮含量显著降低,此时根际脲酶活性同样显著降低.揭示出施钾水平不仅会直接影响烟草根际氮细菌、氮古菌的群落结构,还会影响土壤氮素有效性、土壤酶活,进而影响氮营养的供应和烟草品质.建议前期适量施肥,并在打顶后追施钾肥,改变根际钾环境,提高烟草品质.%To improve the quality of tobacco cultivation, eff ect of diff erent potassium levels on nitrogenous metabolism, nitrogen bacteria and nitrogen archaea bacteria communities in rhizosphere was syudied by means of high-throughput sequencing and spectrophotometric method. Specific results are followed. First, at the growth period with increasing amounts of potassium, the relative abundance of denitrifying bacteria and nitrate reducing bacteria decreased while the ability of reducing nitric nitrogen decreased. Second, available nitrogen was higher and increased by 20.9% than control when N:K2O=1:2.1. Third, the quality of tobacco which was revealed by chemical ingredient was higher when N:K2O=1:2.1. Fourth, at later maturing period, the nicotine was out of suitable range while sugar and potassium were below, which resulted in decreased upper leaves quality. But at the same time, total nitrogen decreased at N:K2O=1:3.5-4.2, along with urease activity. These results showed that diff erent potassium levels aff ected not only community structure of nitrogen bacteria and nitrogen archaea, but also nitrogen availability and enzyme activity, which further resulted in changes of leaf quality and quantity. It was suggested that N:K2O=1:2.1 (236.25kg K2O per hectare) could be applied to increase nitrogen utilization in soil, and dressing potassium fertilizer after topping would be required to altere rhizosphere condition and improve leaf quality.