Studies of winter oilseed rape (Brassica napus L.) very low in aliphatic glucosinolate content | Etudes sur le colza d'hiver (Brassica napus L.) a tres faible teneur en glucosinolates aliphatiques

French. Glucosinolate level of present double low varieties of oilseed rape (Canola type) is low enough to obtain good body weight gain in animal production. Nevertheless enlarged thyroid gland and changes in its metabolism is usually observed. Glucosinolate split products accumulate in circulating extraction solvent. They are chemically very active so can diminish the value of oil. Therefore breeding for further elimination of aliphatic glucosinolates from rapeseed is desired and purposeful. Crosses between the best double low lines of winter oilseed rape were made and individuel selection were carried on in segregating generations of hybrids with the use of selfing and chemical analyses. Obtained population of 1151 inbred lines (S2-S90, F4-F11) were analyzed on glucosinolate content and composition. These lines despite intensive selection in previous generations and achieved very low aliphatic glucosinolate content still indicate substantial differentiation of this trait. Histograms for individual and total aliphatic glucosinolates are continuous and asymmetric with longer sloop in direction to higher values. Histogram for 4-hydroxybrassicin is symmetric. This glucosinolate is present only in seed. Selection pressure was not given to this glucosinolate nevertheless its coefficient of variability is lower than for aliphatic glucosinolates after selection, 21 per cent and about 50 per cent respectively. Investigations made on two generations of lines with very low glucosinolate content show that estimated variability of this trait is still heritable and further selection can be efficient. New lines extremely low in glucosinolate helped to break the strong linkage between the high glucosinolate content and restorer gene for CMS Ogura