The relationship between root morphology and cadmium accumulation in seedlings of two durum wheat cultivars

Two cultivars of durum wheat (Triticum turgidum L.) with known, and differe nt, grain-Cd accumulation were used to compare root tissue accumulation of Cd with root morphology. Six-day-old 'Kyle' and 'Arcola' seedlings were exp osed to a range of Cd2 + concentrations (3.91 x 10(-8) - 3.91 + 10(-7) M) f or 0-200 min, and root Cd contents for the two cultivars were compared with root morphological characteristics. 'Kyle' roots contained 35% less Cd per root system after 200 min of exposure and had less root surface area and f ewer root tips than 'Arcola'. 'Kyle' roots also contained 30% less Cd per g ram of dry weight than 'Arcola' roots after 200 min of exposure. 'Kyle' roo ts also had fewer root tips per unit of root dry weight and less surface ar ea per unit of dry weight (DW) than 'Arcola'. When cadmium concentration da ta (mu g.g(-1) DW) were expressed per unit of root surface area (mu g.cm(-2 )) and per number of root tips (mu g.tip(-1)), the difference in root Cd co ntent between the two cultivars was smaller. These results suggest that gre ater root Cd content of 'Arcola' than 'Kyle' can be explained by difference s in morphology, specifically that a greater surface area and more root tip s in 'Arcola' leads to greater Cd accumulation in root tissue.