Evaluation of the Allelopathic Potential of Aqueous Leaf Extracts of Selected Rashi Vanam Species on the Germination and Seedling Growth of Vigna radiata (Green gram).

Abstract

Allelopathy plays a significant role in regulating plant–plant interactions through the release of bioactive secondary metabolites that influence germination and early seedling development. The present study investigated the allelopathic potential of aqueous leaf extracts of five selected Rashi Vanam species—Azadirachta indica, Elaeocarpus sphaericus, Ficus religiosa, Pterocarpus santalinus, and Tectona grandis—on the germination and seedling growth of Vigna radiata (L.) R. Wilczek under controlled laboratory conditions. Aqueous extracts were prepared at three concentrations (25%, 50%, and 100%), and their effects were evaluated in terms of germination percentage, root length, shoot length, and seedling vigor index (SVI). The results revealed a clear concentration-dependent response. Among the tested species, Elaeocarpus sphaericus and Azadirachta indica exhibited strong inhibitory effects, significantly reducing germination and seedling growth parameters, particularly at 100% concentration. Root growth was more severely affected than shoot growth, indicating higher sensitivity of radicle development to allelochemicals. In contrast, Ficus religiosa, Pterocarpus santalinus, and Tectona grandis showed negligible to mild stimulatory effects at lower concentrations, suggesting a hormetic response. The response index (RI) values further confirmed the inhibitory potential of Elaeocarpus sphaericus and Azadirachta indica, while other species exhibited neutral or slightly positive effects. The study demonstrates that allelopathic effects are species-specific and concentration-dependent. The strong inhibitory potential of certain Rashi Vanam species highlights their possible application in natural weed management, while also indicating the need for careful species selection and spatial planning in agroforestry systems. Further studies focusing on the isolation and characterization of allelochemicals are recommended to better understand their mechanisms of action.