GROWTH, YIELD AND QUALITY OF CANOLA EXPRESSING RESISTANCE TO ACETOLACTATE SYNTHASE INHIBITING HERBICIDES

On Canadian prairies, weed control is a limitation to successful canola production which may be overcome by development of herbicide-resistant cultivars. The csr1-1 gene from Arabidopsis thaliana L., known to confer increased resistance to the acetolactate synthase inhibiting herbicide, chlorsulfuron, was transferred into spring canola (Brassica napus L.). Greenhouse and field experiments were conducted to determine the level of resistance and the yield and quality response of this transgenic canola to the acetolactate synthase herbicides chlorsulfuron, metsulfuron, imazethapyr, imazamethabenz, and flumetsulam. In the greenhouse, transgenic canola expressed higher levels of resistance to all herbicides except imazethapyr applied at the five-leaf than the one-leaf stage. In field studies, inserting the csr1-1 gene into canola did not alter maturity, seed yield, weight, or oil content. Transgenic canola resistance to the acetolactate synthase herbicides varied within and among chemical classes. The ranking of increased tolerance of transgenic canola to these herbicides in the field was chlorsulfuron (9- to 15-fold) > flumetsulam (6- to 10-fold) > imazamethabenz (3- to 6-fold) > metsulfuron (2- to 5-fold) > imazethapyr (1- to 2-fold).