Javid Gherekhloo; Mohammad Hasan Rashed Mohassel; Mehdi Nassiri Mahallati; Eskandar Zand; Ali Ghanbari; Maria D. Osuna; Rafael De Prado
Volume 6, Issue 1 , October 2008
Abstract
During 2005 and 2006, fourteen and seven Phalaris minor populations were found in the wheat fields of Fars and Golestan Provinces, respectively, that exhibited resistance to fenoxaprop-P ethyl and diclofop methyl belonging to the aryloxyphenoxy propionate herbicides. Seed bioassay was conducted at the ...
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During 2005 and 2006, fourteen and seven Phalaris minor populations were found in the wheat fields of Fars and Golestan Provinces, respectively, that exhibited resistance to fenoxaprop-P ethyl and diclofop methyl belonging to the aryloxyphenoxy propionate herbicides. Seed bioassay was conducted at the weed science laboratory of Ferdwosi University of Mashhad to study the resistance of the populations to the APP herbicides. Petri dish assay showed that the populations are resistant to applied herbicides with different level of resistance. Using the estimated parameters of concentration-response curves, discriminating concentration was determined fordiclofop methyl at 8.04 ppm and for fenoxaprop-P-ethyl at 1.05 ppm. A study was also conducted at the agricultural biochemistry laboratory of Cordoba University to investigate the biochemical basis of resistance to ACCase–inhibiting herbicides in the resistant populations. In vitro enzyme assays revealed a herbicide-resistant ACCase enzyme in the AR, MR4 and SR3 populations. Extracted ACCase enzyme from the shoots of these populations was highly resistant to both applied herbicides compared with the susceptible population. The results suggest that the mechanism of resistance to APP herbicides in the three most resistant populations (AR, MR4 and SR3) relates to an altered ACCase. In the case of the rest of the resistant populations, other mechanisms including enhanced metabolism, lack of absorption and translocation, and other unknown mechanisms may be involved. These results also confirmed seven populations are cross-resistant to both the herbicides studied.
Ebrahim Izadi; Mohammad Hassan Rashed Mohassel; Eskandar Zand; Mehdi Nassiri mohalati; Amir Lakzian
Volume 5, Issue 4 , July 2008
Abstract
Atrazine is the most important triazine herbicides with moderately persistence in soil. The objective of this investigation was to study the degradation of atrazine (50 ppm) in two soils different in texture. Experiment was conducted in completely randomized design with factorial arrangement and 3 replications. ...
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Atrazine is the most important triazine herbicides with moderately persistence in soil. The objective of this investigation was to study the degradation of atrazine (50 ppm) in two soils different in texture. Experiment was conducted in completely randomized design with factorial arrangement and 3 replications. Experimental factors included, soil texture(sandy loam and silty clay) and organic manure (0, 2 and 5 percent(w/w)). Soil samples were incubated at 30 oC and dark conditions for 0, 20, 40 and 60 days. At the end of each incubation period, atrazine residue was measured with HPLC. Data was fitted to first order kinetic equation for analysis. Results showed that soil texture and organic manure had significant effects on atrazine degradation rate. Atrazine degradation rate in clay soil with no organic amendment was 1.54 times higher than sandy soil and its half life were 138.6 and 90 days in two soil respectively. Atrazine degradation coefficient increased by 1.14 , 1.8 times in sandy loam soil and by 1.54 , 2.46 times in silty clay soil with 2 percent and 5 percent organic amendment, and the half-life decreased from 138.6, days to 121.57 and 77 days in sandy soil and from 90, days to 58.22 and 38 days in clay soil. It seems that atrazine degredation in silty clay soil is more than sandy loam soil and soil organic manure have an important role in atrazine bioremediation.
