Accumulation and Relationship of Essential Micro-Nutrients with Aluminum Uptake in Winter Canola (Brassica napus) Cultivars.

Species in the Brassica genus representing canola (B. napus and B. rapa) have been classified as phyto-accumulator for their characteristics to accrue some elements at levels which are toxic to other plant species. Since many Brassica species are consumed as green vegetables, accumulation of some elements past a certain threshold may be toxic to the consumers. Five canola (B. napus) cultivars were grown at pH 5.3 in a Decatur silty-loam soil at the Alabama A&M University Agricultural Research Station, and were analyzed for copper (Cu), iron (Fe), manganese (Mn), zinc (Zn) and aluminum (Al) content in their leaves at the rosette, budding and blooming growth stages. Results for the essential micronutrients, Fe, Cu, and Zn indicated no significant difference among the five canola cultivars. The range content of these minerals in leaf tissues were:  23.7 – 25.3 mg/100g dry wt. for Fe; 0.27 – 0.31 mg/100g dry wt. for Cu; and 2.9 – 3-1 mg/100g dry wt. for Zn. However, result for Mn indicated significant difference among cultivars, with Jetton at 18.3 mg/100g dry wt. having significantly greater manganese content than Abilene and Wichita with 15.1 and 15.4 mg/100g dry wt. respectively. Concentration of the non-essential element Aluminum ranged between 16.7 – 24.3 mg/100g dry wt. in leaf tissues, with no significant difference among cultivars. Regression analysis also showed significant linear relationship (r² = 0.89) between Al and Fe accumulation in leaf tissues. Fe and Al decreased, while Cu, Zn and Mn increased in the leaf tissues as plants transitioned from rosette, to budding, and blooming growth stages.