THE EFFECT OF SITE AND FOLIAR SULFUR ON OILSEED RAPE - COMPARISON OF SULFUR RESPONSIVE AND NONRESPONSIVE SEASONS

The effect of foliar sulfur application on the glucosinolate content and yield of a high glucosinolate and a low glucosinolate variety of winter oilseed rape was determined on both high and low sulfur sites. Results from two seasons were compared. At the low sulfur site, sulfur application had no effect on yield in the first, non sulfur responsive season, whereas in the second, sulfur responsive season, sulfur application more than doubled yield of both varieties. Yield at the high sulfur site was not influenced by sulfur application in either season. It is suggested that variations in yield response may be due to differences in the extent of root growth. In many cases glucosinolate content was increased by sulfur application, even when yield was not affected. The glucosinolate content of the high glucosinolate variety responded more to sulfur application than that of the low glucosinolate variety. The implications of these findings are discussed.