SESSION-8: Restoration Methodologies and Conservation Strategies
PAPER-6: Phytotoxicity of Phenolic Allelochemicals to Aquatic Weeds with reference
to Conservation, Restoration and Management of Aquatic Ecosystems
Pandey D. K. and Mishra N.

Abstract:

The study was aimed at investigating phytotoxicity of allelochemicals viz. o-, m- and p- anisic acids; o-, m- and p- coumaric acids; caffeic acid, caffeine anhydrous, catechol, chloremphenicol and cinnamic acid to six floating aquatic weeds Eichhornia crassipes Mart Solmns. Salvinia molesta Mitchell, Pistia stratiotes L., Azolla nilotica Decne., Spirodela polyrhiza L. Schleid. and Lemna pausicostata Hegelm.; and four submerged weeds - Hydrilla verticillata L. f. Royle, Ceratophylum demersum L . , Najas graminea Del. and Chara sp. The aquatic weeds were allowed to grow in solutions of the test allelochemicals in a quarter strength standard nutrient medium in plastic containers outdoors. Biomass of the weeds was monitored after 5 and 10 days. Toxicity of the allelochemicals varied with species. The chloramphenicol was lethal to Chara sp. at relatively very low concentration (one- fiftieth the lethal level for other aquatic weeds) and this has implications on management of the weed using the allelochemical (an antibiotic) as a circumstantial allelochemic herbicide for an aquatic ecosystem especially in fisheries. Alternatively, it may be an idea that an organism releasing the allelochemical at substantial concentration into the medium could be found out for facilitating management of the weeds especially Chara sp. in aquatic ecosystems. Accumulation of the allelochemicals may affect conservation, restoration and management of aquatic ecosystems.