جستجوی مقالات مرتبط با کلیدواژه « مقاومت » در نشریات گروه « محیط زیست »

To evaluate the resistance of wild oat (Avena ludoviciana), annual ryegrass (Lolium rigidum) and littleseed canarygrass (Phalaris spp.) in wheat fields of Fars, Khouzestan, Golestan and Ilam Provinces of Iran to clodinafop-propargyl herbicide from ACCase inhibitors of aryloxyphenoxy propionate classes, 6 separate indoor experiments were conducted in the greenhouses of the Department of Weed Research in the Iranian Research Institute for Plant Protection. The experiments were conducted by using 19 populations of wild oat (including 15 questionably resistant populations and 4 susceptible populations), 14 littleseed canarygrass populations (including 10 suspected-resistant populations and 4 susceptible populations) and 9 annual ryegrass populations (including 8 questionably resistant populations and 1 susceptible mass) from Fars Province, 4 populations of wild oat (including 3 questionably resistant populations and 1 susceptible mass)from Lorestan Province, 17 littleseed canarygrass populations (including 16 probably resistant populations and 1 susceptible mass) from Khouzestan Province, and 12 littleseed canarygrass populations (including 11 questionably resistant populations and 1 susceptible mass) from Golestan Province. All the experiments were conducted separately in the form of a Randomized Complete Block Design (RCBD). A pot under no-herbicide application was also included as control. The remaining weeds number and dry weight percentage were calculated 30 days after herbicide application, and were then compared with their relative figures before herbicide application. A mass was recognized resistant only if it retained80% of its number and 50% of its dry weight, in comparisonto the control. On this basis, 4 resistant and 2 questionably resistant littleseed canarygrass populations, 6 resistant and 3 questionably resistant wild oat populations and 5 resistant and 3 questionably resistant Annual Ryegrass populations were identified in Fars Province. In Ilam Province, 2 resistant wild oat populations were identified. Overall, in this experiment 75 populations including 63 questionably resistant and 12 susceptible populations were evaluated. Amongst the 63 questionably resistant populations (including 37 littleseed canarygrass, 18 wild oat and 8 annual ryegrass populations), 28 totally resistant populations (including 12 littleseed canarygrass, 11 wild oat and 8 annual ryegrass populations) and 10 probably resistant (consisting of 4 littleseed canarygrass populations, 3 wild oat populations and 3 annual ryegrass populations) were detected. In other words, approximately 60% (44% resistant and 16% probably resistant) of all evaluated questionably resistant populations were identified as resistant and probably resistant.

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 for diclofop 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.