Toxicity of the norflurazon to the aquatic macrophyte Vallisneria americana (Michx.).
Vallisneria americana (Michx.) (common name tapegrass) is a submersed, vascular aquatic plant that reproduces vegetatively and by seed. The objective of this study was to determine the no-observable-effects concentrations (NOECs) and lowest-observable-effects concentrations (LOECs) for tapegrass exposed to the herbicide norflurazon (0-0.1 mg/L) following a 14-d exposure and a postexposure period. The primary symptom of norflurazon toxicity was bleaching of newly emerged leaf blades at concentrations of 0.04 mg/L and higher after 14 d of exposure. Leaf greenness effect levels were 0.04 mg/L (NOEC) and 0.06 mg/L (LOEC). All other endpoints measured resulted in a NOEC greater than 0.1 mg/L following the exposure period. Latent effects were observed 14 d postexposure for new leaf production and fresh weight gains, with a NOEC and LOEC of 0.08 and 0.1 mg/L, respectively. Total leaf growth was the least sensitive endpoint measured. Following the exposure/postexposure periods, significant effects on vegetative reproduction were apparent, with no effects occurring at concentrations up to 0.08 mg/L, but with significant reduction at the 0.1 mg/L treatment level. Root and stolon dry weights were significantly reduced at the 0.1 and 0.08 mg/L treatments, respectively. Total soluble sugars (TSS) and hexose content in shoots was reduced at concentrations of 0.04 mg/L and higher. TSS, hexose, and sucrose contents were higher in roots of plants exposed to 0.1 mg/L. Some recovery was apparent for all treatment concentrations following the postexposure period, indicating that the effects were at least partially reversible.[1]References
- Toxicity of the norflurazon to the aquatic macrophyte Vallisneria americana (Michx.). Wilson, P.C., Wilson, S.B., Haunert, D. J. Toxicol. Environ. Health Part A (2006) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg