ScienceAsia 27 (2001) : 099-104 |doi: 10.2306/scienceasia1513-1874.2001.27.099

The Effect of Carbamate Insecticide on the Growth of Three Aquatic Plant Species: Ipomoea aquatica, Pistia stratiotes and Hydrocharis dubia

Siriorn Boonyawanich^a, Maleeya Kruatrachue^a, E Suchart Upatham^a, Puangpaka Soontornchainaksaeng^b, Prayad Pokethitiyook^a and Sombat Singhakaew^a

ABSTRACT: The purpose of this study was to assess the effects of carbamate insecticide on the growth of three aquatic plant species, Ipomoea aquatica, Pistia stratiotes and Hydrocharis dubia. These three aquatic plant species were treated with different concentrations of carbaryl and test durations. The fresh weight increase, the dry weight per fresh weight and the total chlorophyll content of the treated plants decreased with increasing concentrations of carbaryl and the test durations. The leaf injury indices of the treated plants increased with increasing concentrations of carbaryl and the test durations, while the leaf injury indices of the controls were zero. The 96-hour EC₅₀ values of total chlorophyll content of I. aquatica, P. stratiotes and H. dubia were 0.996, 0.785 and 0.334 g/l, respectively. Moreover, chlorosis and necrosis occurred at the leaf margin of the treated plants, then they extended into the inner portion of the leaf blade. Finally, the leaves decayed and the plants died.

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a Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
b Department of Plant Science, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.

Received 31 Mar 2000, Accepted 9 Feb 2001