Phosphate-solubilizing microbes in rhizosphere soils of 19 weeds in southeastern China

摘要

Low phosphorus (P) availability is one of the most important factors limiting plant growth in red soils across southeastern China. Many non-symbiotic microorganisms in rhizosphere can enhance P solubility, hut little is known about the magnitude of their phosphorus-solubilizing ability (PSA) and the difference in phosphorus-solubilizing microorganisms (PSM) among plant species. The rmmber of phosphorns-solubilizing microorganisms and their PSA in rhizosphere soils of 19 weed species in a citrus orchard on red soil at Changshan, Zhejiang, China, were investigated. Inorganic P (powdered phos-phate rock, PR) and orgatfic P (lecithin, OP) were respectively used as the sole P-souree to examine the PSA of isolated microbes. The PS actinomycetes community varied greatly among the different weed rhizospheres while the PS fungus community showed to be most stable to the weed rhixosphere.The highest number of PR-PS and OP-PS bacteria was found in rhizos, phere soil of Mollugo pentaphyll and the highest nuraber of PR-PS and OP-PS actinomycetes was found in rhizosphere soil of Polygonum lapathlfollum. The highest number of PR-PS fungi was found in Erigeron annuus and Mollugo pen-taphyll rhizosphere soil, and the highest number of OP-PS fungi was found in rhizosphere soil of Maxus stachydifolius. Mazus stachydifolius showed the strongest PR-PS ability (6340.75μg) while Eragrostis pilosa showed the strongest OP-PS ability (1301.84μg). The PR-PS ability and OP-PS ability of Mollugo pentaphyll was 4432.87μg and 1122.05μg respectively. A significant correlation between the number of PR-PSM and OP-PSM was found. Significant correlation was only found between the PR-PS fungi number and its PSA( r = 0.75, P < 0.05 ) and between the number of OP-PS fungi and its PSA( r=0.87, P<0.011 ). It indicated that plant species had significant influence on components of the non-symbiotic PSM community and their activity in its rhizosphere soil. Fungi play a l~ role inphosphorus solubilization in weed rhizopshere. It suggested that weed conservadoncould benefit soil microbe development in agroecosystems, especially in the initial stage of agroecosystam develolmaent because there is less organic carbon in bare soil. The results suggested that weed conservation could increase PSA of PSM.