FACTORS CAUSING VARIATION IN GLUCOSINOLATES IN OILSEED RAPE

It is now well established that considerable variation occurs between locations and seasons in seed glucosinolate concentrations even in the newer double-low varieties entering the national lists. Agronomic trials have demonstrated that little of the variation is attributable to the practices used to grow the crop. Our research has shown that concentrations of glucosinolates increase during seed growth, and that the final concentrations tend to be proportional to seed size and to be lower in crops in which the ratio of sulphur to seed number is small. It is known that drought at particular stages of growth increases glucosinolate concentrations and that the duration of seed growth depends on environmental conditions and varies between years. However, the underlying physiological mechanisms are not fully understood and variations in seed glucosinolates cannot confidently be predicted.