Table 1.

Characteristics of the five herbicides used in Arabidopsis thaliana (Col-0) and Brassica napus (Westar) gene expression studies

Trade name	Manufacturer	Mode of action	Chemical family	Active ingredient (a.i.)
Arsenal™a	BASF Corporation, Research Triangle Park, NC, USA	ALS inhibitor	Imidazolinone	Imazapyr
Beacon™	Syngenta Crop. Protection Inc., Greensboro, NC, USA	ALS inhibitor	Sulfonylurea	Primisulfuron-methyl
FirstRate™	Dow AgroSciences LLC, Indianapolis, IN, USA	ALS inhibitor	Triazolopyrimidine	Cloransulam-methyl
Oust™	E.I. du Pont de Nemours and Company, Wilmington, DE, USA	ALS inhibitor	Sulfonylurea	Sulfometuron methyl
Roundup original™	Monsanto Company, St. Louis, MO, USA	EPSPS inhibitor	–	Glyphosate

Trade name	% a.i.	A.th. treatment concentration (g ha−1 a.i.)b	B.n. treatment concentration (g ha−1 a.i.)b
Arsenal™a	53.1	0.395	1.429
Beacon™	75.0	0.586	9.058
FirstRate™	84.0	0.163	0.549
Oust™	75.0	0.131	0.886
Roundup original™	41.0	10.652	79.745

Abbreviations: ALS acetolactate synthase, EPSPS 5-enolpyruvylshikimate-3-phosphate synthase, A.th. Arabidopsis thaliana, B.n. Brassica napus. Treatment concentrations were determined to result in comparable reductions in growth (“Materials and methods”). In addition to active ingredients, the herbicides contain inert components indicated in Material Safety Data Sheets

^aApplicators concentrate

^bThe herbicide rates [% of the field application rate active ingredient (f.a.r. a.i.)] estimated to produce a 50% reduction in shoot dry weight based on nonlinear regression analysis of data from a range-finding dose response study. A probit model was used to identify the EC₅₀ values for A.th., while the Weibull model, which was developed later for use in these herbicide studies, was used with B.n.. For B.n. and Roundup Original™ the herbicide concentration used was enough to cause approximately 60% reduction in shoot dry weight based on the Weibull model