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QUIK STATS (last updated Jan 20, 2015 )
NOTES ABOUT THIS BIOTYPE
Full Paper Here: http://www.weedscience.org/Documents/ShowDocuments.aspx?DocumentID=1344
Evaluación de la resistencia de una población de Echinochloa colona L. a los herbicidas glifosato y fluazifop- p- butil Alvaro Anzalone1; Dany Peña2 y Deryk García 21Departamento de Fitotecnia. 2Estudiantes graduados. Decanato de Agronomía. Universidad Centroccidental “Lisandro Alvarado”. Apartado postal 400.Venezuela. aanzalone@ucla.eduve
ABSTRACT
Resistance to glyphosate and fluazifop-p-butyl herbicide of a Echinochloa colona L. population Echinochloa colona L. is one of the most important weed in rice crop under direct sowing in Venezuela and its control mainly is based on the use of herbicides. The inefficient control of populations of this weed by glyphosate and fluazfop-p-butyl in rice fields in Cojedes state, made think the resistance occurrence, reason why it was carried out be this evaluation. The field affected by the problem was sampling and seeds of the weed were collected (resistant population); also seeds of the same weed in a field in ecological production were collected where applications of herbicide have been made never (susceptible population). The used methodology is based on the proposal by Seefeldt et al. (1995). It was used a completely randomized design with 6 treatments (herbicide dose) and 22 repetitions for each population and herbicide evaluated. Each repetition consisted of a pot with 2 to 3 plants of the weeds. The doses of herbicide evaluated were: 0; 21,88; 43,75; 87,5¸175 and 350 g.ha-1 of fluazifop-p-butil and 0; 337,5; 675; 1350; 2700 and 5400 g.ha-1 for glyphosate. Passed 21 days it was come to determine the aerial fresh weight of the plants for the calculation of the weight average by plant in each repetition. The data was analyzed by analysis of variance and fit to log-logistic model of dose-response for the calculation of the resistance index (RI). The evaluated population was resistant to both herbicides, obtaining a RI= 2.25 for fluazifop-p-butil and RI=4,18 for glyphosate.
ACADEMIC ASPECTS
CONTRIBUTING WEED SCIENTISTS
ACKNOWLEDGEMENTS
BACKGROUND This study confirms and characterises glyphosate resistance in two polyploid Echinochloa colona populations from north-eastern Australia.
RESULTS Glyphosate dose response revealed that the two resistant populations were marginally (up to 2-fold) resistant to glyphosate. Resistant plants did not differ in non-target-site foliar uptake and translocation of 14C-glyphosate but contained the known target-site EPSPS mutation Pro-106-Thr and/or Pro-106-Leu. Although plants carrying either a single or two EPSPS mutations were glyphosate-resistant relative to the susceptible population, they were still controlled at the field rate of glyphosate (450 g a.e. ha−1) when treated under warm conditions (25/20 °C). However, when treated in hot conditions (35/30 °C), most mutant resistant plants (68%) can survive the field rate, and an increase (2.5 fold) in glyphosate LD50 was found for both the R and S populations.
CONCLUSIONS This study shows that one or two EPSPS Pro-106 mutations are insufficient in conferring field-rate glyphosate resistance in polyploidy E. colona at mild temperatures. However, control of these mutant plants at the glyphosate field rate is poor at high temperatures, likely due to reduced glyphosate efficacy. Therefore, glyphosate should be applied during relatively mild (warm) temperature periods in the summer growing season to improve E. colona control.
BACKGROUND: Echinochloa colona is an annual weed affecting field crops and orchards in California. An E. colona population carrying a mutation in the EPSPS gene endowing resistance to glyphosate, the most widely used non-selective herbicide, was recently identified in the Northern Sacramento Valley of California. Plants from this population, from a suspected glyphosate-resistant (GR) population, and from one susceptible (S) population collected in the Northern Sacramento Valley of California, were used to generate three GR and one S selfed lines to study possible mechanisms involved in glyphosate resistance. RESULTS: Based on the amount of glyphosate required to kill50%of the plants (LD50), GR lines were 4–9-fold more resistant than S plants and accumulated less shikimate after glyphosate treatment. GR and S lines did not differ in glyphosate absorption, translocation or metabolism. A different target-site mutation was found in each of two of the GR lines corresponding to Pro106Thr and Pro106 Ser substitutions; the mutations were found in different homoeologous EPSPS genes. No mutation was found in the third GR line, which exhibited 1.4-fold higher basal EPSPS activity and a fivefold greater LD50 than S plants. Quantitative RT-PCR revealed that GR lines had similar or lower EPSPS expression than S plants.
CONCLUSION: It is demonstrated that individuals with different glyphosate resistance mechanisms can coexist in the same population, individuals from different populations may carry different resistance mechanisms and different mechanisms can act in concert within single E. colona plants. However, other plant factors or resistance mechanisms appear to modulate plant expression of EPSPS sensitivity to glyphosate.