覆盖模式及小麦根系对土壤微生物区系的影响

采用平皿分离培养法研究了5种栽培模式和小麦根系对土壤细菌、真菌及放线菌数量的影响。连续2年的定位测定结果表明:覆膜有利于土壤微生物数量增加。5种栽培模式中,小麦根区、根外土壤细菌数量均以覆膜模式下最高,分别为116.8×106cfu·g-1和86.7×106cfu·g-1;土壤真菌和放线菌数量均以垄沟覆膜(垄上覆膜、垄沟播种)模式下最高,分别为3.0×103cfu·g-1、1.4×103cfu·g-1和18.9×105cfu·g-1、19.7×105cfu·g-1。不同模式下小麦根系对土壤细菌和真菌数量影响较大,表现为根区高于根外;而根系对放线菌影响较小,只有补灌和覆膜2种模式为根区高于根外。多重比较结果显示,覆膜与其他模式之间细菌数量差异极显著,根区土壤细菌和真菌数量与根外存在显著差异。覆盖和根系能大幅度增加根区细菌、真菌和放线菌的数量,强化小麦根区根外细菌和真菌的数量差异。

Effect of mulching mode and wheat root on soil microbial flora

Five cultural modes of wheat were established and the amount of soil bacteria, fungi and actinomycetes in both the rhizosphere and bulk soil of wheat determined using plate culture method. The 2-year orientation experiment shows that plastic film mulching significantly increases soil microbial population. Under plastic film mulching, the number of soil bacteria in wheat rhizosphere and bulk soil(respectively 116.8 × 10⁶cfu·g^-1 and 86.7 × 10⁶cfu·g^-1) are highest among the 5 treatment modes. The number of soil fungi and actinomycetes in wheat rhizosphere and bulk soil under ridge plastic film mulch furrow cultivation are 3.0 × 10³cfu·g^-1, 1.4 × 10³cfu·g^-1 and 18.9 × 10⁵cfu·g^-1, 19.7 × 10⁵cfu·g^-1 respectively. The amount of soil bacteria and fungi in the rhizosphere is higher than that in bulk soil of wheat, indicating that wheat root has a significant effect on soil bacteria and fungi. However, root effect on actinomycete is weak only with high actinomycete population in the rhizosphere than bulk soil under plastic film mulching and supplemental irrigation. Multiplex comparison shows significant differences in bacteria population between plastic film mulching and the other 4 modes; and bacteria and fungi population between the rhizosphere and bulk soil. The results suggest that mulching and wheat root increase microbial population and widen the difference between bacteria and fungi in the rhizosphere and bulk soil.