Heavy metal (Cr, Cu, Zn, As, Cd, and Pb) contamination in irrigation water, soil, and vegetables was investigated in farmland adjacent to a multi-industry zone in Bangladesh in dry and wet seasons. In the zone, many factories release wastewater into nearby irrigation canals, and vegetables cultivated with this water could be a major food chain route for human exposure. In the irrigation water and vegetables, heavy metal concentrations exceeded permissible levels in the two seasons, but this was not the case in soil. Zn had the highest concentration, and Cd had the lowest concentration in irrigation water, soil, and vegetables. All heavy metal concentrations were found to be lower in the wet than in the dry season, which is due to the dilution of water by rainfall, lower absorption of heavy metals from the diluted irrigation water, and heavy metal absorption from low concentrated irrigation water and/or soil. The cluster analysis data of irrigation water, soil, and vegetables revealed that the heavy metals in vegetables were considered to be absorbed from irrigation water in the wet season and from soil in the dry season. In the dry season, the high heavy metal concentrations in vegetables might be caused by a high bioconcentration factor (mostly > 20%).

Specifically primed polymerase chain reaction (PCR) analysis was used for direct detection and identification of Rhizoctonia solani isolates belonging to AG 1 subgroups (IA, IB, and IC) and AG 2 subgroups (2-1 and 2-2). A rapid DNA extraction method with a solution of sodium hydroxide was conducted to extract PCR templates. PCRspecific primer sets for each group were designed from sequences in the regions of the 28S ribosomal DNA of this fungus. The results of specifically primed PCR analysis showed that AG 1-IA, AG 1-IB, AG 1-IC, AG 2-1, and AG 2-2 primers sets contributed detection from the same AG isolates and could escape detection from different AG isolates at a high level of frequency. In this experiment, we suggested that our synthesized primer sets might provide a method for the direct detection and identification of AGs of R. solani.

Soil saprophytic fungi isolated from the waste paper sludge were identified by ITS genes sequencing. Their antagonistic effects on mycelial growth of Fusarium oxysporum f. sp. lycopersici (FOL) were tested in vitro, and Trichoderma virens, 911 (Tv911) had inhibited 60.35％ of the growth compare to control. Moreover, it was selected for investigating plant growth promoting abilities on Japanese mustard spinach, tomato and radish in manufacturer recommended soils, farmer use nursery soil (FNS) and home garden soil (HGS). Plant height of one-month old Japanese mustard spinach and tomato were increased 16.22％ and 50.26％ in treated FNS and 9.84％ and 7.00％ in treated HGS in comparison with non-treated control, respectively. Fresh shoot and root weight of radish were also increased 23.83％ and 58.86％ in treated FNS and 12.77％ and 64.45％ in treated HGS. Disease suppression of Tv911 against FOL was also examined, and disease severity of fusarium wilt of tomato was significantly reduced. Additionally, the Tv911 colonization was observed as a stable in soil and increased in root tissue over growing period of one month. Therefore, this strain has the potential for plant growth promotion and diseases suppression against FOL, and it would be useful as a biological agent in crop production.