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Glyphosate resistance in Echinochloa colona : phenotypic characterisation and quantification of selection intensity
Author(s) -
Goh Sou Sheng,
VilaAiub Martin M,
Busi Roberto,
Powles Stephen B
Publication year - 2016
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.4005
Subject(s) - glyphosate , fecundity , biology , population , echinochloa , selection (genetic algorithm) , resistance (ecology) , agronomy , botany , zoology , horticulture , veterinary medicine , weed , demography , medicine , artificial intelligence , computer science , sociology
Abstract BACKGROUND A population of Echinochloa colona infesting agricultural fields in the northern region of Western Australia evolved glyphosate resistance after 10 years of glyphosate selection. This study identified two phenotypic (susceptible S versus resistant R) lines from within a segregating glyphosate‐resistant population. Estimation of survival, growth and reproductive rates of the phenotypes in response to glyphosate selection helped to characterise the level of resistance, fitness and the selection intensity for glyphosate in this species. RESULTS Estimations of LD 50 (lethal dose) and GR 50 (growth rate) showed an eightfold glyphosate resistance in this population. The resistant index based on the estimation of seed number (SY n 50 ) showed a 13‐fold resistance. As a result of linear combination of plant survival and fecundity rates, plant fitness values of 0.2 and 0.8 were estimated for the S and R phenotypes when exposed to the low dose of 270 g glyphosate ha −1 . At the recommended dose of 540 g glyphosate ha −1 , fitness significantly decreased (fivefold) in S plants but remained markedly similar (0.7) in plants of the R phenotype. Thus, the calculated selection intensity (SI) at 540 g glyphosate ha −1 was much greater (SI = 17) than at 270 g glyphosate ha −1 (SI = 4). CONCLUSIONS The assessment of plant survival and fecundity in response to glyphosate selection in the S and R phenotypes allowed a greater accuracy in the estimation of population fitness of both phenotypes and thus of glyphosate selection intensity in E. colona . The estimation of seed number or mass of phenotypes under herbicide selection is a true ecological measure of resistance with implications for herbicide resistance evolution. © 2015 Society of Chemical Industry