A quick test for glyphosate resistance in annual ryegrass

Aaron Preston, Joseph Moore, James Pratley, Gabriel Thelen

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Annual ryegrass is the most economically damaging winter crop weed in Australia. Effective control measures are key to minimising management costs and yield loss. Glyphosate is an effective herbicide used in post-emergent control of annual ryegrass, although continuous use has led to the evolution of herbicide resistance. Early and rapid identification of resistant plants facilitates control measures for resistant populations and helps minimise their spread. Some methodologies have been developed for the quick testing of glyphosate resistance in Lolium spp. The aim of this study was to assess a further methodology, using un-germinated and pre-germinated seed, for speed, simplicity and accuracy in determining phenotype. Four biotypes of annual ryegrass, two glyphosate resistant and two susceptible, were selected to evaluate the
capability of the test to segregate between resistant and susceptible populations. The performance of the pre-germinated assay was compared with an assay using un-germinated seed. Seeds were placed on filter paper within Petri dishes containing glyphosate concentrations of 0, 2.5, 10 and 40 mg ae/L. Dishes were then placed in a growth incubator. After 7 days, root lengths were measured. Both assays were able to differentiate between resistant and susceptible biotypes. Differences in root length inhibition were greatest amongst samples with lower concentrations of glyphosate, with 2.5mg ae/L providing the greatest segregation for un-germinated seed (43% inhibition for susceptible versus resistant biotypes). The higher dosage of 10mg ae/L provided greater phenotype discrimination in pre-germinated seed (61% inhibition for susceptible versus resistant biotypes). Both pre-germinated and un-germinated seed assays provided a quick and simple method to identify glyphosate resistance in annual ryegrass
Original languageEnglish
Title of host publicationBuilding Productive, Diverse and Sustainable Landscapes
Place of PublicationWarragul; Victoria; Australia
PublisherAustralian Society of Agronomy
Number of pages4
Publication statusPublished - 2015
Event17th Australian Agronomy Conference - Wrest Point Convention Centre , Hobart, Australia
Duration: 21 Sept 201524 Sept 2015


Conference17th Australian Agronomy Conference
Abbreviated titleBuilding Productive, Diverse and Sustainable Landscapes
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