Allelopathy is defined as any direct or indirect, catastrophic effect of a plant on another plant through the release of chemicals into the soil environment. Plants produces some chemical compound and releases then in the environment which is called as allelochemicals. These allelochemicals shows beneficial or harmful effects on seed germination, growth, and progress of other plants. A number of studies have indicated that the Ageratum conyzoides have the allelochemicals potential. It releases various types of allelochemicals such as flavonoids, Alkaloids, saponins, tannins, cardiac glycosides, anthraquinones, gallic acid, ferulic acid, coumaric acid, hydroxybenzoic acid anisic acid and syringic acid. These allelochemicals may be harmful or helpful for the plant growth and the development. Pisum sativum (pea) is a valuable pulse crop cultivated in India. It is one of the major pulse crop of Uttar Pradesh grown in Rabi season. The present work has done to investigate allelopathic effects on some biochemical parameters such as chlorophyll, proline, protein, leghaemoglobin, nitrogen, phosphorous, and nitrate and nitrite reductase enzyme activity.
