Variation in cadmium concentration in seed and its association with phenotypic traits of 166 diverse flax (<i>Linum usitatissimum</i> L.) pure lines grown in western Canada

Four field trials were conducted in western Canada in 2020 and 2021 to assess cadmium (Cd) concentration in seed from 166 pure lines of flax originating from 26 countries that were derived by single seed descent from a genetically diverse flax core collection preserved by Plant Gene Resources of Canada. Associations of Cd concentration with morphological and phenological traits, as well as the country of origin were considered. The mean Cd concentration in the seed ranged from 0.31 to 1.50 mg/kg with an overall mean value of 0.93 ± 0.22 mg/kg. The Cd in the soil from the field sites ranged from 0.35 to 2.80 mg/kg and was positively correlated with the Cd concentration in the seed harvested from the respective sites. The consistency of the Cd concentration in the seed of pure lines across the four site-years was low, with correlation coefficients ranging from 0.35 to 0.53. Pure lines with consistently low Cd concentration in the seed were identified and may be useful for breeding linseed cultivars for human consumption while pure lines with consistently high Cd concentration might be used for phytoremediation of Cd-contaminated soils. Cd concentration in the seed was not significantly correlated with thousand seed weight, plant height, petal colour, seed colour, or country of origin. As a tendency, the longer the vegetative period and the later the accessions matured, the more Cd they accumulated in the seed. For linseed production in western Canada, choosing locations with a low Cd content in the soil is very important when growing flax for human consumption or feed use.