Plant Science Research, Vol. 35, 2013

Degradation of chemically related organochlorine pesticides (γ - hexachlorocyclohexane and vinclozolin) in rice soil, pre-exposed to each other

Accelerated degradation of soil-applied pesticides, upon their repeated application, is the result of proliferation of microorganism degrading candidate pesticide and can undermine the efficacy of the pesticide under consideration. In the present study, experiments were conducted both in green house and in laboratory conditions to examine the development of enhanced degradation of vinclozolin in mineral salts medium inoculated with soil suspension from unplanted and planted flooded alluvial soils untreated or pre-treated with commercial HCH and vice versa. Results demonstrated that 15 days after fourth application, approximately 97% of vinclozolin was degraded in the suspension from planted pots. The development of enhanced biodegradation of ã-HCH was examined in a mineral salts medium inoculated with soil suspensions from unplanted or planted flooded alluvial soils untreated or pre-treated with commercial vinclozolin. Fifteen days after third application, only a trace of ã-HCH was recovered from the soil suspension from planted pots. The rice plants played a definite and important role in influencing the development of enhanced degradation of both the pesticides.