Abstract
In a trial to evaluate the impact of one of the commonly used insecticides in Egypt, a plot area cultivated with soybean was sprayed with endosulfan. Some of the biochemical criteria of the treated soybean and the biodiversity and biochemical activity of its companion cyanobacteria were compared with those of the untreated ones. The results revealed that endosulfan application caused inhibition in the attendance and biodiversity of the soil cyanobacteria found in the rhizosphere of the treated soybean, specially the filamentous species. The treated soil showed a highly significant inhibition in their ARA (acetylene-reducing activity) and exopolysaccharides. The biochemical analysis showed a high significant decrease in all the carbohydrate fractions as well as DNA and RNA contents of the treated soybean plants compared with the untreated ones. However, the total soluble proteins significantly Increased, indicating some defense pattern against the lethal effects of endosulfan. From the results, it could be concluded that application of endosulfan has a significant potential to change ecosystems and soil biological processes and could potentially reduce future farm productivity and cause harmful impact to agriculture.