Chairman: Dr. Peeter Noges & Dr. M. A. Khan
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
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.
Physiology Section, National Research Centre for
Weed Science (ICAR), Maharajpur, Jabalpur (M.P.) 482004, India
Phone: 0761-353101 (O); 353934