Mohssen Elbagoryand Howida El-Habet( 2019). Effect of Herbicides on Different Soil Microbial Population in Transplanted Rice.Egy. J. Plant Pro. Res. 7 (2): 15-37 (2019)
Abstract: This study was conducted to investigate the effect of recommended doses from thiobencarb 50% EC, penoxsulam 24% SC and pendimethalin 50% EC herbicides on the microbial activities of N2-fixing cyanobacteria, nitrifiers, sulfate-reducing bacteria, N2-fixing bacteria and total aerobic bacteria count) at regular intervals i.e. 2nd to 30th day after treatment under transplanted rice during 2017 and 2018 seasons. The results revealed that native N2- fixing cyanobacteria, nitrifying bacteria, nitrogen-fixing bacteria and total bacterial count, were increased with penoxsulam application. On the other hand, sulphate reducers were decreased in both seasons compared with application of thiobencarb, pendimethalin and the untreated control. For N2-fixing cyanobacteria, the highest populations was observed on 12th day (15.15×103 g-1 soil and 16.95×103 g-1 soil), then it gradually decreases on 30th day (5.19 ×103 g-1 soil and 5.15×103 g-1 soil) during 2017 and 2018 seasons, respectively. But, at 16th days of treatment the higher enumeration of nitrifiers bacteria were (1.03×103 g-1 soil and 1.12×103 g-1 soil), during 2017 and 2018 seasons, respectively, over control treatment then decreased thereafter at the end of the experiment (30th days). On the other hand, the treated and untreated soil showed decreasing in total count of sulphate reducing bacteria with different days after treatment. Also, application of penoxsulam herbicide enhanced the counts of N2-fixing bacteria and total aerobic bacteria with lapse of time after treatment during the two growing season. Therefore, use of penoxsulam has no negative effects on the soil microbial diversity and reflected on growth and productivity of rice.
Keywords: (Microbial activities; N2-fixing cyanobacteria; nitrifiers; sulfate-reducing bacteria; N2-fixing bacteria; total aerobic bacteria count.)
