Dual Behariour of Carbaryl and 2,4-Dichlorophenoxyacetic Acid in Rhizobium leguminosarum 2005 under Explanta Conditions

Abstract

Summary Studies have shown that major pesticide (carbaryl) and herbicide (2,4-D) at higher concentrations (50 μg/ml) were inhibitory to the Rhizobium growth but they stimulated oxygen uptake in a concentration dependent manner. Extremely low concentration of carbaryl (1 μg/ml) and 2,4-D (5 μg/ml) treated culture showed enhanced growth. Nitrate Reductase (NR) and Nitrite Reductase (NiR) activities increase in the presence of 125 μg/ml concentration of carbaryl (1-napthyl methyl carbamate) and 300 μg/ml.of 2,4-D (2,4-Dichlorophenoxy acetic acid). Further increase in concentration led to decline in NR and NiR activities. Dual behaviour of these chemicals may be due to their action as electron donors and thereby causing alteration through oxidative metabolic pathway. It is suggested that besides pesticidal and herbicidal action, carbaryl and 2,4-D may also be used as well to harness the beneficial effects of nitrogen fixing organisms.