Abstract

Allelopathy is described as both beneficial and deleterious biochemical interaction between plant and weeds, and/or plant and microorganisms through the production of chemical compounds that escape into the environment and subsequently influence the growth and development of neighbouring plants. The present laboratory experimental study was conducted to evaluate the allelopathic effect of Cassia sophera (L.) on three weed plants (Chenopodium album L., Melilotus alba Medik and Nicotiana plumbaginifolia Viv.). Aqueous extracts of Cassia at 0.5, 1.0, 2.0 and 4.0% concentrations were applied to determine their effect on seed germination, seedling growth, dry biomass, leaf area, relative water content, chlorophyll and protein content of test plants under laboratory conditions. The aqueous extracts had a significant retardatory effect on seed germination of test plants which varied among species and also with the different concentrations used. Root length and shoot length of weed species decreased significantly when plants were exposed to increasing aqueous concentration (0.5, 1, 2 and 4%). The noticed reduction in dry biomass, leaf area and relative water content were also significant. Physiological parameters (total chlorophyll content and protein content) in relation to three test species (M. alba, C. album and N. plumbaginifolia) were significantly reduced with the different concentrations of aqueous extract used. From this we can predict that cassia might possess allelochemicals that causes the suppressive ability.

Key words: Allelopathy, aqueous extract, Melilotus alba, Chenopodium alba and Nicotiana plumbaginifolia.

Abbreviation

Abbreviations: DAS, Day after sowing; CRD, completely randomized design; AOSA, Association of Official Seed Analysts; DMSO, di-methyl sulphoxide; CSAE, C. sophera aqueous extract; GP, germination percentage; PL, plumule length; RL, radicle length; DW, dry weight; RWC, relative water content.