Effect of sulphur application on lipid, RNA and fatty acid content in developing seeds of rapeseed (Brassica campestris L.)

Changes in the contents of lipid, RNA and fatty acids were determined in the developing seeds of rapeseed (Brassica campestris L. cv. Pusa Gold) grown with or without sulphur. In + S treatments, S was applied either as a single dose (T-2) or the same dose was split in two (T-3) or three (T-4) portions. Rapid accumulation of lipids started at 7 days after flowering (DAF) and continued until 35 DAF. Application of S increased the lipid content in the seeds from the initial stage. The maximum increase was observed, when S was applied in three portions. There was a positive strong co-relation between S and lipid content in the seeds. RNA content increased from 7 to 35 DAF, followed by a decline until maturity. Application of S increased the RNA content in the seeds, compared to control (T-1). Among the +S treatments, i.e. T-2, T-3 and T-4, the treatment T-4 resulted in the maximum increase in RNA of developing seeds. The fatty acid composition of the oil changed substantially during seed development. S application in three portions increased the oleic acid (18:1) content, and decreased the erucic acid (22:1) content over other treatments. This leads to a reduced 22:1/18:1 ratio and thus, improves the quality of oil. The ratio of erucic acid to oleic acid (22:1/18:1) is closely related to the N:S ratio in the seeds. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.