Influence of insecticide phorate on chemical composition and enzyme profile of root exudates and root extracts of Brassica juncea

摘要

'Rhizosphere effect', a phenomenon of enhanced degradation of pollutants in rhizosphere is frequently reported, however the underlying mechanism is poorly understood. It is known that root exudates play a significant role in this phenomenon. Thus, the effect of phorate present in the growth medium on the composition of root exudates and extracts of Brassica juncen was studied in the preset investigation. Results indicated significant increase in proteins (88.4 and 26.2%), total glutathione (13.2 and 58.3%), and ascorbic acid (13,4 and 100%) content of root exudates and root extracts, respectively of the plants when grown in presence of phorate. An increase in riboflavin concentration was observed incase of root extracts only. On the contrary, no significant changes were observed in total carbohydrate, free thiol groups, amino acids, sugars, antioxidative enzymes, phenolic acids and flavonoids present in root exudates and extracts of plants in presence of phorate. Results of the present investigation provide some limited but preliminary evidence on the fact that exudation behaviour of roots was altered on sensing the presence of contaminants (phorate) in the rhizosphere, which can be one of the reasons for rhizospher effect.