富钾烤烟品种成熟期根系分泌物和根际细菌多样性特征分析

Characteristics of root exudates and rhizosphere bacterial diversity of potassium-enriched flue-cured tobacco genotype at mature stage

[目的]研究不同钾吸收利用效率烤烟品种成熟期根系分泌物和根际细菌多样性差异,有助于了解烟草富钾品种成熟期高效吸收利用钾素的机理。[方法]选用富钾烤烟品种ND202和常规品种K326、NC89进行盆栽试验,分析了不同烤烟品种成熟期根际主要养分含量、根系分泌物和根际细菌多样性的差异。[结果]成熟期NC89和ND202根际土中的碱解氮和有效磷含量极显著低于K326,速效钾含量3个品种间差异极显著,且为ND202最低。成熟期ND202非根际土的碱解氮极显著高于K326和NC89,有效磷和速效钾含量3个品种间差异极显著且均为ND202最高。3个品种成熟期根系分泌物主要成分含量有差异,ND202根系分泌物有机酸含量占其已检测出根系分泌物总量的 81.80%,比NC89高12.86%,比K326高15.98%。3个烤烟品种成熟期根际和非根际土壤主要细菌在门水平和属分类水平上相对丰度有较大差异。根际土壤中链霉菌属、气微菌属和Iamia属的相对丰度表现为ND202>K326>NC89,而芽孢杆菌属、硝化螺菌属、乳酸乳球属、Steroidobacter属、Flavisolibacter属和野村菌属的相对丰度则表现为ND202<K326<NC89。[结论]成熟期富钾品种ND202具有根际土壤速效钾含量较低而非根际速效钾含量较高、根系分泌物有机酸含量高的特点。成熟期不同钾吸收利用效率烤烟品种的根际土壤与非根际土壤细菌多样性有显著差异。

In order to understand the mechanism of potassium uptake and utilization in potassium-enriched tobacco genotype, the diversity of root exudates and rhizosphere bacteria in flue-cured tobacco varieties with different potassium uptake and utilization efficiencies at mature stage were studied. Pot experiment was carried out with potassium-enriched flue-cured tobacco variety ND202 and conventional varieties K326 and NC89 as material to analyze differences in main nutrient contents, root exudates and rhizosphere bacterial diversity in rhizosphere soil at maturity stage. The content of available nitrogen and phosphorus in NC89 and ND202 rhizosphere soil was significantly lower than that of K326 at maturity stage. There existed extremely significant difference in available potassium content among all 3 varieties (ND202 ranked the lowest). The available nitrogen in ND202 non rhizosphere soil at maturity stage was signi ficantly higher than that of K326 and NC89. Extremely significant difference also existed in contents of available phosphorus and potassium among all three varieties, with ND202 ranked the top. The contents of main components in root exudates of all 3 varieties were di fferent. The content of organic acids in ND202 root exudates accounted for 81.80% of the total root exudates, which was 12.86% higher than that of NC89 and 15.98% higher than that of K326. Relative abundances of the main bacteria in rhizosphere and non rhizosphere soil of the 3 flue-cured tobacco varieties were di fferent at phylum and genus level. The relative abundances of Streptomyces, Aeromicrobium and Iamia in rhizosphere soils followed the order as ND202>K326>NC89;while the relative abundances of Bacillus, Nitrospira, Lactococcus, Steroidobacter, Flavisolibacter and Nonomuraea could be ranked as ND202<K326<NC89. Potassium -enriched variety ND202 had lower available potassium in rhizosphere soil, higher available potassium in non rhizosphere soil and high organic acid content in root exudates at maturity stage. There was a significant difference in bacterial diversity between rhizosphere soil and non rhizosphere soil for flue-cured tobacco varieties with different potassium uptake and utilization efficiency at maturity stage.