جستجوی مقالات مرتبط با کلیدواژه « resistance factor » در نشریات گروه « زراعت »

Little mallow is a common weed in wheat fields of Khuzestan province, which is often controlled by tribenuron-methyl and 2,4-D+MCPA, from acetolactae synthase inhibitors and synthetic auxin herbicides. Recently, there have been some reports about poor control of this plant with these herbicides, especially in wheat fields of Southern Khuzestan. Therefore, due to the lack of research on the occurance of mallow resistance to the mentioned herbicides and to estimate the resistance level among the mallow populations, little mallow seeds were collected from wheat fields in southern Khuzestan and whole plant assays were carried out in the pot. Dose-response results revealed that the resistance factor (RF) based on fresh weight for resistant (R) populations to tribenuron-methyl, and 2,4-D+MCPA were 2.05-10.11 and 2.51-3.09 fold higher than susceptible (S) plant, respectively. Similarly, the resistance factor (RF) based on survival plants for resistant (R) populations to tribenuron-methyl, and 2, 4-D+MCPA were 2.14-34.93 and 1.99-2.91 fold higher than susceptible (S) plant, respectively. The E population, however, was not significantly different from S population in response to tribenuron-methyl.

In order to investigate the resistance of short spike canarygrass (Phalaris brachystachys) biotypes to acetyl coenzyme A carboxylase inhibiting herbicides wheat fields of Golestan province, 43 suspected resistance were collected from a different area in 2018. The susceptible biotype was also collected from regions with no chemical control record. The study was carried out in three steps including determination of discriminating concentration for susceptible biotype, screening P. brachystachys biotypes with the discriminating concentrations, and concentration-response experiment for suspected resistant biotypes at Gorgan University of Agricultural Sciences and Natural Resources in 2018. According to the seed bioassay test, the discriminating concentration of sensitive biotype for clodinafop propargyl, diclofop methyl, haloxyfop-r-methyl, cycloxydim and pinoxaden were 0.02, 1.36, 0.03, 0.06 and 0.08 mg a.i.L-1, respectively. In the screening test using the discriminating concentration, 36 (84%), 36 (84%), 19 (44%), 23 (53%), 21 (48%) out of 43 biotypes were identified as suspected resistant to clodinafop propargyl, diclofop methyl, haloxyfop-R-methyl, cycloxydim and pinoxaden, respectively. In general, the results showed that the studied biotypes had different patterns in terms of resistance to different groups of ACCase-inhibiting herbicides. The results of the concentration-response test also showed that among 43 suspected resistance suspected of resistance, 19 biotypes were resistant to all five herbicides.

More than twenty years after registration of tribenuron methyl herbicide in Iran, there are reports on its lack of efficacy in controlling broad leaved weeds in wheat fields of Ramiyan Township. To investigate the occurrence of resistance to tribenuron methyl in wild mustard (Sinapis arvensis L.), a series of experiments were conducted at Gorgan University of Agricultural Sciences and Natural Resources in 2016. Putatively resistant wild mustard biotypes were gathered from wheat fields of the Township. A susceptible biotype was also gathered from the fields with no history of spraying. Putative biotypes were first screened with the recommended dose. Then, response of susceptible and resistant biotypes to various doses of tribenuron methyl herbicide was investigated. The results of dose-response assay implied occurrence of resistant to tribenuron methyl in some wild mustard biotypes. Resistance factors of RAM-R-14, RAM-R-27, RAM-R-25, RAM-R-30 and RAM-R-5 were obtained respectively 3.90, 4.10, 3.96, 2.66 and 2.36. Distribution map of fields infested with susceptible and resistant wild mustard biotypes was drawn using geographic information system and it was revealed that the gathered biotypes were observed in the fields which possessed unsuitable cropping pattern and weed management was based on chemical control. The results of the present study may be utilized to implement herbicide-resistant weed management practices as well as prevention of development of these plants to other regions.

Wheat is the most important crop in Iran and every year about 6.5 million ha of arable lands in the country is cultivated by this strategic crop. Weeds cause 23 to 30% reduction in yield of wheat annually. Winter wild oat is the most serious grass weed of wheat fields of Iran. Chemical method is the common way to weed control in wheat fields. ACCase inhibitors such as clodinafop-propargyl, diclofop-methyl and Fenoxaprop-P ethyl + Mefen pair di ethyl are widely used for control of grasses in this regard. Continuous application of herbicides with the same mode of action has resulted in developing herbicide resistant biotypes of weeds such as Avena ludoviciana. The objectives of the current study were: 1) to screen the collected accession of A. ludoviciana suspected to resistance to FOP herbicides, 2) to determine the resistance factor of resistant biotypes and 3) mapping distribution of resistant biotypes. In order to survey Avena ludoviciana resistance to clodinafop-propargy, diclofop-methyl and Fenoxaprop-P ethyl+ Mefen pair di ethyl herbicides in wheat fields of Gonbad-e Kavus, several experiments were conducted in 2014 at Gorgan University of Agricultural Sciences and Natural Resources. (115 populations). The seed bioassay in Petri dish and pot experiment was conducted to determine resistance to acetyl coenzyme Acaboxylase inhibitors (ACCase), respectively. The seed bioassay experiment consisted of screening the suspected populations with discriminating concentration and concentration-response bioassay for resistant populations. In 48, 27 and 21 populations of A. ludoviciana were resistant to clodinafop-propargyl,
diclofop-methyl and Fenoxaprop-P ethyl + Mefen pair di ethyl herbicides. Resistance accessions indicated varying degrees of resistance to tested herbicides. Based on EC50, the lowest and highest resistance to Clodinafop-propargyl herbicide was shown in Accessions of 74 and 6 with resistance factors of 1.99 and 31.42, respectively. Also for Diclofop- methyl herbicide, EC50 values from 2.88 for accession of 103 (with 1.34 resistanc factor) to 16.02 for accession of 91 (with 7.45 resistance factor) were different. In addition, EC50 estimatedfor Fenoxaprop-P ethyl + Mefen pair di ethyl herbicide was different from 0.124 to 0.86 for 20 and 6 accessions, respectively. Checking the distribution map of resistance accessions showed these accessions had uniform distribution in this city. Based on these observations, the existence of cross-resistance to herbicides was proved in some of the collected accessions. The results of this study can be used to correct programs designed to manage weeds herbicide resistance and prevent of the development of the plants in other areas.

Littleseed canarygrass (Phalaris minor) is one of the most important weeds in wheat and barley fields of Iran. Recently a biotype (SR3) of this weed has been detected in wheat fields of Fars province which has developed resistance to clodinafop-propargyl, fenoxaprop-P-ethyl and diclofop-methyl herbicides. In order to investigate the cross-resistance of SR3 biotype to cyclohexanedione and phenlypyrazolin herbicides, a dose-response assay was conducted at Gorgan University of Agricultural Sciences and Natural Resources during 2011. In the experiment, response of sensitive (ES) and resistant (SR3) biotypes were assayed by spraying the seedlings with 0, 0.25, 0.5, 1, 2, 4, 8, 16, and 32-fold of the recommended field dose of tralkoxydim, pinoxaden and sethoxydim herbicides. Results indicated that the ES biotype was 50% controlled with 140.26, 13.16 and 89.54 g ai ha-1 of tralkoxydim, pinoxaden and sethoxydim herbicides, respectively, while the amount of herbicides that controlled 50% of the SR3 biotype were 1863.32, 372.18 and 89.54 g ai ha-1, respectively. Resistance factor (RF) of SR3 biotype for tralkoxydim, pinoxaden and sethoxydim herbicides estimated as 13.28, 28.29 and 9.82, respectively. Results confirmed the cross-resistance in SR3 biotypes to APP, CHD and PPZ herbicides.