Macro-nutrient Status of Brassica napus and Brassica juncea Grown Under Swedish Conditions

Concentrations and amounts of macro-nutrients (N, P, K, Ca, Mg, S) in shoots, vegetative and generative plant parts in B. napus and B. juncea and nutrient inflow per unit root length in B. napus were studied in a field experiment at Uppsala, Sweden. Concentrations in vegetative plant parts were, except for Ca in B. napus, highest at the beginning of the season, and N and K were higher in B. napus than in B. juncea. The higher N concentration in vegetative parts (leaves, stems and pods) in B. napus was probably due to differences in growth pattern between the species. Seed concentrations of N, P, Ca, Mg and, most pronounced of all, S were higher in B. juncea. Nutrient amounts were, with the exception of K, throughout the season higher in B. juncea than in B. napus due to a higher dry matter production. Nutrient inflow per unit root length in B. napus was highest during the rosette stage for all nutrients. During flowering, the inflow decreased for N and K and increased for P and Ca. After root growth had stopped, no net inflow of K and S was found and inflow rates of other nutrients were at very low levels.