The effect of intensity of selection during successive generations of seed multiplication, on the field performance of Brussels sprouts

Abstract

An experiment in which two different intensities of selection were applied, in each of three successive generations, to two varieties of Brussels sprout showed that the progeny resulting from lax selection were frequently inferior in agronomic characteristics to those from the more stringent selection. In one of the varieties used, this inferiority took the form of an increase in the proportion of off-types, and in the other there was a decrease in yield.

These results imply that deterioration in the agronomic value of a variety is likely to occur whenever standards of selection are relaxed, for example, to accelerate the multiplication of seed. It is suggested that such deterioration is most likely to occur in those characteristics for which selection has improved the uniformity of a variety but has produced only partial homozygosity over the range of loci affecting those characteristics.