Changes of microbial population in different rootzones of 'TifEagle' bermudagrass during establishment

摘要

Microbes play important roles in soil nutrient cycling, thatch decomposition and antagonism towards pathogens. As turfgrass and golf industry are blooming in China in the past few decades, concerns arise regarding the role of sand-based rootzones of putting green as a favorable habitat for the development of microbes. The objective of the study was to examine the effects of different soil mixtures on the dynamic changes of soil microbial population and the turf quality during the first year of establishment. A greenhouse study was conducted with "TifEagle' bermudagrass [Cynodon dactylon (L.) x C. transvaalensis Burtt-Davy] planted in the pots with five types of rootzones as follows: sand (A), native soil (B), sand mixed with native soil (C) (85: 15 v/v), sand mixed with peat (D) (85: 15, v/v); sand mixed with native soil and peat (E) (85: 7.5: 7.5 v/v/v). Microbial populations (bacteria, Bacillus spp., actinomycetes, and fungi), hydrolysable nitrogen (HRN) and organic matter (OM), and turfgrass quality were evaluated bimonthly and root and shoot biomass were determined at the end of the study. During the first-year establishment, bacteria and fungi populations increased from 6.79-7.02 to 7.27-7.43 lg cfu g(-1) dry soil and from 4.36-4.58 to 5.82-6.35 lg cfu g(-1) dry, respectively for sand-based rootzones but not Bacillus spp. and actinomycetes two months after planting, coupling with the decrease in soil OM and HRN. A decline in bacteria, Bacillus spp., and fungi occurred four months after planting, and maintained stable after six months of planting. Turfgrass quality was positively correlated with microbial population in Bacillus spp. (r=0.43, p0.001) and actinomycetes (r=0.50, p0.001) and soil nutrient status in HRN (r=0.55, p0.0001) and OM (r=0.65, p0.0001). Sand-based rootzone mixtures were adequate to maintain turfgrass quality (6.4-7.6) and microbial population. Grasses grown in them had higher root:shoot ratio (1.92-2.06) than pure sand (0.75) and native soil (0.50) alone.