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.