Morphological and biochemical responses of Macrotyloma uniflorum (Lam.) Verdc. to allelopathic effects of Mikania micrantha Kunth extracts

Yield loss due to noxious weeds is one among several reasons for the reduced economy for the developing countries. Impacts of one such weed i.e. Mikania micrantha were investigated on the rate of seed germination, growth, biomass, photosynthetic pigments, total soluble protein, phenolics and proline content of leaves of Macrotylama uniflorum (an important pulse). In a completely randomized setup, control and four concentrations (10 mg/ml, 50 mg/ml, 100 mg/ml and 200 mg/ml) of the aqueous leaf extracts of M. micrantha were tested on the seeds of M. uniflorum. The extracts inhibited germination, growth, biomass, chlorophyll, carotenoid and protein contents. The protein content of M. uniflorum decreased to 8.48 mg/g at 200 mg/ml. Similarly, shoot length and root length were also decreased up to 5.11 cm and 0.85 cm respectively and water content increased with the increasing concentration of weed extracts. The leaf extracts resulted in an increase in the phenolics (19.66 mg) and proline (24.49 mg) content of the crop plant. The preliminary study indicated that the aqueous leaf extracts of weed plant resulted in negative or detrimental impact on growth and physiology of the plant and this might be due to the release of secondary metabolites. The present investigation may further lead to the identification of certain secondary metabolites or allelo-chemicals that may have an important agricultural application for sustainability and may enhance the level of crop protection against several other harmful plant species.