Predicting decreases in Canola (Brassica napus and B-rapa) oil and meal quality caused by contamination by Brassicaceae weed seeds

Canola (edible rapeseed) crops are often infested by related weed species. This paper addresses effects that seeds from various Brassicaceae weeds may have on canola oil and meal quality. Seeds of common Brassicaceae weeds we re collected from canola fields throughout northern Idaho. These were wild mustard, black mustard, birdsrape mustard, shepherd's-purse, flixweed, tumb le mustard, and field pennycress. Collected seeds were physically described by weight, size, and shape and were analyzed for oil concentration, fatty acid composition, and glucosinolate concentration. Seed weights ranged from 0.1 to 2 g/1,000 seed. Oil concentration in the weed seeds ranged from 25 to 38%, with erucic acid levels ranging from less than 1 to 47%. Glucosinol ate concentration in the mustard weed seeds was over 100 mu mol/g oil-free meal, except for shepherd's-purse, which had only 3.4 mu mol/g. Using these data, a simple model predicts that both canola oil and seed meal quality c an be adversely affected by contamination with weed seeds. Increased erucic acid concentration in modeled admixtures was the most Likely oil quality p roblem associated with weed seed contamination. Glucosinolate concentration in modeled admixtures was higher than acceptable only in those admixtures that also had erucic acid levels that exceeded canola quality standards. Ca nola-quality oil and seed meal can be maintained with conspicuous weed seed mixtures up to the 2% maximum allowed in U.S. No. 1 canola. However, canol a-quality oil and seed meal was not achieved when a 5% weed seed mixture al lowed in No. 2 canola was evaluated with the model.