Inbreeding depression and single cross hybrids in leeks (Allium ampeloprasum ssp. porrum)

Summary All current commercial cultivars of leeks are open-pollinated and one of the major problems with the crop is poor uniformity with much of the variation being genetic in origin. Inbred lines and single cross hybrids were produced to try to reduce the genetic variation. Inbreds were generated by single seed descent from 5400 plants taken from six commercial cultivars and performance data for uniformity, yield and quality are presented for the S₁-S₃ generations. A few relatively vigorous inbred lines were obtained but overall, inbreeding depression was very severe with no compensating increase in uniformity as measured by coefficients of variation. In contrast, the experimental hybrids gave significant uniformity, yield and quality benefits compared to open-pollinated commercial cultivars and can be used as the basis for developing a range of commercial hybrid cultivars.Abbreviations SSD Single Seed Descent - HRI Horticulture Research International