Effects of allelochemical extracts from medicinal plants on physiological and biochemical mechanisms of maize (Zea mays L.) seedlings

Abstract Aqueous extract of Ricinus communis and Lantana camara contains substances that have allelopathic potential on maize (Zea mays L.). The present study showed that different concentrations of the water soluble leaf extracts of R. communis and L. camara inhibit the germination and growth of maize. These extracts also affect activity of some enzymes. Leaf aqueous extracts of both the plants were made to determine their effects on germination, seedling growth, fresh and dry weight of root and shoot and their effects on activity of superoxide dismutase (SOD), peroxidase (POD), Catalase (CAT), polyphenoloxidase (PPO) of root and shoot and lipidperoxidatio (MDA) of root of 8 d old maize seedlings. Results revealed that higher concentration of Lantana camara leaf extract exhibited significant inhibitory effect on germination and seedling growth. The biochemical assay indicate that the Ricinus communis and Lantana camara leaf extracts at higher concentration of 1.2% have increased the SOD, POD and CAT activity of root as compared to control. The enzyme activity of shoot was not significantly increased by the Ricinus communis and Lantana camara leaf extract except the catalase activity. The allelopathic effect of these extracts was more pronounced on root than the shoot parts. The higher concentration of extracts had stronger inhibitory effects, whereas the lower concentrations showed stimulatory effect in some cases.