CHANGES IN GLUCOSINOLATES DURING CROP DEVELOPMENT IN SINGLE-LOW AND DOUBLE-LOW GENOTYPES OF WINTER OILSEED RAPE (BRASSICA-NAPUS) .1. PRODUCTION AND DISTRIBUTION IN VEGETATIVE TISSUES AND DEVELOPING PODS DURING DEVELOPMENT AND POTENTIAL ROLE IN THE RECYCLING OF SULFUR WITHIN THE CROP

The distributions of glucosinolates and sulphur were measured in the vegetative and reproductive tissues in a series of single- and double-low cultivars of oilseed rape (Bienvenu, Ariana, Cobra and Capricorn) grown on a sulphur-sufficient soil at Rothamsted in 1987/88, and in crops of the cv. Libravo grown with none or 40 kg/ha of sulphur on a sulphur-deficient soil at Woburn in 1990/91. The glucosinolate measurements demonstrated large differences in the abilities of single- and double-low cultivars to synthesise glucosinolates, and showed that the biosynthetic differences were associated more with the developing pods than the vegetative tissues. It indicated that potential contribution of intact glucosinolates from vegetative tissues to the seed was likely to be small, but did not preclude the possibility that the vegetative tissues were a source of glucosinolate precursors. The sulphur measurements showed that the glucosinolates contained only a small proportion of the crop's total sulphur and that they were unlikely to be a major source of recyclable sulphur, even under conditions of severe sulphur deficiency.