Identification of Genes Controlling Pod Length in Spring Rapeseed, Brassica napus L., and their Utilization for Yield Improvement

Experiments were undertaken to determine the inheritance of pod length in a cross with spring rapesecd, Brassica napus, and to assess the value of pod length as a criterion of selection for high seed yield. Analyses of patterns of variation in F2; and backcross populations derived from a cross between a short‐pod line TB42 and long‐pod line CA553 indicated that much of the variation in pod length could be attributed to two major genes interacting in a complementary manner. Short‐pods were produced when cither one or both genes were homozygous for the recessive allele. Analyses of F3 progenies of selected F2 and inbred‐backcross lines derived from the same cross supported the two‐gene hypothesis but also indicated that the effects of the major genes on pod length were possibly modified by genes of minor effect. Field testing of families derived from random intermating between F2, plants of the TB42 × CA553 cross showed that number of pods per plant varied independently of pod length, but seed weight per pod tended to increase with increasing pod length. As a result, families with the longest pods generally had significantly higher yields than those with short pods. It was concluded that yield improvement in B. napus could be achieved through introgression of long‐pod genes into cultivars with an appropriate genetic background to ensure that selection for the long‐pod character would be accompanied by an increase in seed weight per pod with little or no reduction in number of pods per plant.