2014 年 5 巻 1 号 p. 125-130
Cassava (Manihot esculenta Crantz) is an important economic crop in Thailand. Nowadays, insect pest is the major problem that causes severe damage to cassava leading to considerable yield losses. Since, using chemical pesticide is always presence of chemical residues on soil and may affect the population and diversity of soil microorganism. Therefore, the aim of the study was to determine the effect of thiamethoxam on plant growth promoting rhizobacteria (PGPR) population in cassava production system. A total of 400 bacteria were isolated from 4 sites, including 1 (cassava production system without thiamethoxam and fertilizer application 2 (cassava production system with thiamethoxam application 3 (cassava production system with thiamethoxam and organic fertilizer application 4 (cassava production system with thiamethoxam and chemical fertilizer application. These isolates were screened for their plant growth promoting factors like production of indole-3-acetic acid (IAA), phosphate solubilizing activity and their ability to grow in N-free medium. In addition, their biocontrol activity like protease and chitinase enzyme production and siderophore production as well as antagonistic activity against Fusarium sp. were investigated. The findings of this study indicated that the application of thiamethoxam in cassava production system can affect PGPR population. In this study, numbers of bacterial isolates demonstrate that they are a potential source to be used as microbial inoculant for crop production system.
