Effects of Legume Residues with and without Allelochemicals on Biodiversity of Plant Growth Promoting Bacteria in Long-Term Organic Residues Amendment Systems

抄録

Application of organic residues into infertile soil is one way to restore the fertility and productivity of arable soils. However, organic residues have different qualities (especially chemical compositions including allelochemicals) that may influence the activity and type of microorganisms present in the soil. Therefore, this study aims to investigate the effect of allelochemicals on plant growth promoting bacteria (PGPB) biodiversity in 17 years long-term field experiment continuous application of different quality residues, groundnut stover (Arachis hypogaea) (high quality organic residue; with allelochemicals) and tamarind (Tamarindus indica L.) (intermediate quality organic residue; without allelochemicals), compare to control (no organic residue applied). PGPB isolates were screened for their plant growth promoting factors such as production of indole-3-acetic acid (IAA), phosphate solubilizing activity and their ability to grow in nitrogen-free medium. In addition, the biocontrol activities which are protease production and antagonistic activity against Fusarium sp. were investigated. PGPB biodiversity was determined on a basis of amplified rDNA restriction analysis (ARDRA). The majority of bacteria were found to belong to the genera of Bacillus, Staphylococcus, and Brevibacterium. In addition, at 52 weeks after residue application, PGPB richness of tamarind treatment was higher than groundnut treatment. The findings of this study also indicated that long-term legume residues amendment with and without allelochemicals can affect PGPB richness and biodiversity.