CADMIUM UPTAKE AND BIOACCUMULATION IN SELECTED CULTIVARS OF DURUM-WHEAT AND FLAX AS AFFECTED BY SOIL TYPE

Accumulation of cadmium (Cd) in crop plants is of great concern due to the potential for food chain contamination through the soil-root inte rface. Although Cd uptake varies considerably with plant species, the processes which determine the accumulation of Cd in plant tissues are affected by soil factors. The influence of soil type on Cd uptake by d urum wheat (Triticum turgidum var. durum L.) and flax (Linum usitatiss imum L.) was studied in a pot experiment under environmentally control led growth chamber conditions. Four cultivars/lines of durum wheat (Ky le, Sceptre, DT 627, and DT 637) and three cultivars/lines of flax (Fl anders, AC Emerson, and YSED 2) were grown in two Saskatchewan soils: an Orthic Gray Luvisol (low background Cd concentration; total/ABDTPA extractable Cd: 0.12/0.03 mg kg(-1), respectively) and a Dark Brown Ch ernozem (relatively high background Cd concentration; total/ABDTPA Cd: 0.34/0.17 mg kg(-1) respectively). Plant roots, stems, newly develope d heads, and grain/seeds were analyzed for Cd concentration at three s tages of plant growth: two and seven weeks after germination, and at p lant maturity. The results showed that Cd bioaccumulation and distribu tion within the plants were strongly affected by both soil type and pl ant cultivar/line. The Cd concentration in roots leaves and stems vari ed at different stages of plant growth. However, all cultivars of both plant species grown in the Chernozemic soil accumulated more Cd in gr ain/seeds than plants grown in the Orthic Gray Luvisol soil. The diffe rent Cd accumulation pattern also corresponded to the levels of ABDTPA extractable and metal-organic complex bound soil Cd found in both soi ls. Large differences were found in grain Cd among the durum wheat cul tivars grown in the same soil type, suggesting the importance of rhizo sphere processes in Cd bioaccumulation and/or Cd transport processes w ithin the plant. Distribution of Cd in parts of mature plants showed t hat durum grain contained up to 21 and 36% of the total amount of Cd t aken up by the plants for the Orthic Gray Luvisol and Chernozemic soil s, respectively. These results indicate the importance of studying Cd speciation, bioaccumulation and cycling in the environment for the man agement of agricultural soils and crops.