Studies on allelopathic potential and biochemical characterization of cassia uniflora and synedrella nodiflora, the dominant invasive weeds from the campus of Pune University

Abstract

The need for research and development in allelopathy for the improvement of agriculture, forestry and ecology is of extreme urgency, because the understanding of allelopathy has major role(s) in the interactions between invasive/ exotic and native weeds, weeds-crops, crops-crops etc. These studies are of utmost importance in agriculture, forestry, ecology and environmental degradation. Many of these weeds cause damages to agroecosystems and disturb natural phytodiversity. Their dominance, luxuriant growth, persistence throughout the year, tolerance to biotic and abiotic stress conditions and allelopathic potential might be the probable factors of successful invasion in new habitats. To explicate the phenomenon of very high dominance of weeds like Cassia, Synedrella, Alternanthera, Acalypha and Euphorbia which are forming monothickets/ pure stands in the campus of Pune University, were investigated with different approaches like ecophysiological, biochemical and enzymological aspects. At the same time, the allelochemicals existing in these plants were isolated, characterized and identified. It was hypothesized that these selected invasive weeds mostly have negative or sometimes positive allelopathic influence on the other native or even exotic weeds and crops, when they naturally exude or leach out the allelochemicals from intact parts or from the residues. For understanding the basic reasons of invasion and dominance as well as luxuriant growth of these weeds phytosociological, allelopathic potential, morphophysiological, biochemical, enzymological parameters, characterization of allelochemicals were attempted. The studies on cytotoxicity and phytotoxicity of leachates, extracts and residues were undertaken with the purpose to understand the mode and mechanism of action of allelochemicals. The attempts to investigate the larvicidal and antimicrobial activities had contributed to explore and use such untapped weed biomass in sustainable agriculture as the agents of biological control.