An experiment was designed to study the allelopathic effect of Ageratum conyzoides L. on chlorophyll content of the leaves of mungbean (Vigna radiata L.) plants. The mungbean plants were raised by seeds in polythene bags and kept in an open field. These were treated with aqueous extracts of various parts viz. leaves, stem and roots of Ageratum conyzoides. The plants were analyzed for chlorophyll ‘a’, chlorophyll ‘b’ and total chlorophyll content at different stages of its growth. For estimation of chlorophyll healthy and treated plants of 15, 30, 45 and 60 days were taken. A decrease in the contents of chlorophyll a, b and total chlorophyll was observed in all the treated plants as compared to control during all the stages of the growth. The maximum reduction in chlorophyll content was observed in the plants treated with leaf extract followed by those treated with stem extract while the plants treated with root extract did not show much change in chlorophyll content. It was concluded that Ageratum conyzoides cause a reduction in chlorophyll content in mungbean plants by inhibiting its biosynthesis or enhancing its degradation. However these phytotoxic compounds are present in varying concentrations in different parts of the weed.
