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|Title:||Response of multiple herbicide resistant strain of diazotrophic cyanobacterium, <i>Anabaena</i><i style=""> variabilis</i>, exposed to atrazine and DCMU|
|Abstract:||Effect of two photosynthetic inhibitor herbicides, atrazine (both purified and formulated) and [3-(3,4-dichlorophenyl)-1,1-dimethyl urea] (DCMU), on the growth, macromolecular contents, heterocyst frequency, photosynthetic O<sub>2</sub> evolution and dark O<sub>2</sub> uptake of wild type and multiple herbicide resistant (MHR) strain of diazotrophic cyanobacterium <i style="">A. variabilis</i> was studied. Cyanobacterial strains showed gradual inhibition in growth with increasing dosage of herbicides. Both wild type and MHR strain tolerated < 6.0 mg L<sup>-1</sup> of atrazine (purified), < 2.0 mg L<sup>-1</sup> of atrazine (formulated) and < 0.4 mg L<sup>-1</sup> of DCMU indicating similar level of herbicide tolerance. Atrazine (pure) (8.0 mg L<sup>-1</sup>) and 4.0 mg L<sup>-1 </sup>of atrazine (formulated) were growth inhibitory concentrations (lethal) for both wild type and MHR strain indicating formulated atrazine was more toxic than the purified form. Comparatively lower concentrations of DCMU were found to be lethal for wild type and MHR strain, respectively. Thus, between the two herbicides tested DCMU was more growth toxic than atrazine. At sublethal dosages of herbicides, photosynthetic O<sub>2</sub> evolution showed highest inhibition followed by chlorophyll <i style="">a</i>, phycobhiliproteins and heterocyst differentiation as compared to carotenoid, protein and respiratory O<sub>2</sub> uptake.|
|ISSN:||0975-1009 (Online); 0019-5189 (Print)|
|Appears in Collections:||IJEB Vol.49(04) [April 2011]|
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