An experiment under microcosm was conducted to assess the allelochemical potential of Mikania micrantha on the growth andgermination of Lactuca sativa through a pot culture experiment. Soil samples were collected from two different sites i.e., M. micranthainvaded soil (for the experimental pot) and healthy forest soil (for control pot). Various seed germination and growth parametershave been analyzed to evaluate the inhibitory and stimulatory effects of the allelochemicals released from M. micrantha. The resultsrevealed that the germination and growth parameters of the crop were inhibited and suppressed by M. micrantha. Out of the fifteenseeds planted in both pots, thirteen seeds were able to germinate in the experimental pot, while fourteen were in the control pot. Theseedling height (8.85 cm), shoot length (8.75 cm), seedling biomass (0.408 g), vigor index (0.52), root length (0.091 cm), germinationpotential (0.73), germination percentage (86.66%), germination index, (3.66) and germination rate index (317.17) were lower in theexperimental pot and higher in the control pot. Therefore, M. micrantha showed an inhibitory effect on the growth and germination ofL. sativa and induced negative allelopathic effects.

Invasive alien plants like Ageratum conyzoides influence the growth, yield, development, and productivity of food crops. The various allelochemicals present in A. conyzoides exert stimulatory or inhibitory effects on the food crops. In this microcosm investigation through pot experiments, we evaluated the allelopathic potential of A. conyzoides on the germination and seedling growth of a leafy vegetable of nutritional value i.e., Lactuca sativa. The soil samples were collected from two different sites i.e., healthy forest soil and soil invaded by A. conyzoides. The healthy forest soil was considered as control pot while A. conyzoides invaded soil was selected for the experimental pot. The inhibitory effect of the invasive plant was observed on the tested crop of dietary value in human nutrition. The results revealed that the germination of the seeds is inhibited and suppressed by A. conyzoides. Microcosm studies demonstrated that out of the 15 seeds planted on both pots, 13 seeds germinated and thrived on the experimental pot and 14 on the control pot. The seedling height (32.1 cm), shoot length (27.65 cm), seedling biomass (1.866 g) and vigor index (6.829) were recorded higher in the experimental pot. Whereas, the root length (4.8 cm), germination potential (0.93), germination percentage (93.33%), germination index (4.66) and germination rate index (434.91) were noted higher in the control pot. A. conyzoides therefore showed both the inhibitory and stimulatory effects on L. sativa and thereby exhibited both positive and negative allelopathic effects. Further, bioassay experiments with other bioassay crops can elucidate the chemical ecology and allelopathy potential of A. conyzoides