SULFUR UPTAKE AND DISTRIBUTION IN DOUBLE AND SINGLE LOW VARIETIES OF OILSEED RAPE (BRASSICA-NAPUS L)

Sulphur (S) uptake and distribution in double low (Cobra) and single low (Bienvenu) winter oilseed rape were studied in field experiments at Cockle Park, Northumberland, at a site where the S supply was adequate. Total S uptake at maturity of between 80-100 kg ha-1 was similar in both varieties. Applications of S at a rate of 100 kg ha-1 increased S uptake by 10- 15 kg ha-1, while applications of nitrogen (N) at a rate of 300 kg ha-1 increased S uptake by 29-34 kg ha-1. Sulphur distribution in the vegetative tissues varied little between the two varieties but the distribution within the pods differed significantly between the two varieties. In Bienvenu 65.8% of pod S was located in the seeds, while in Cobra 57.4 and 68.8% in the 1988-89 and 1989-90 seasons, respectively, was retained in the pod walls. The high S content of the seeds of Bienvenu was due to their high glucosinolate content, whereas the high content of S in the pod walls of Cobra was associated with the presence of free SO42-, which accounted for 70.6 to 89.4% of total S in the pod walls. The percentages of total plant S present in the pods were significantly increased by N applications and slightly decreased by S applications.