Ovule fertilization and seed number per pod determination in oil seed rape (Brassica napus)

Ovule fertilization in relation to seed number determination in spring rapeseed, Brassica napus var. Maris Haplana, was investigated. Failure of fertilization was found to be the major factor limiting the number of seeds per pod in both the basally and apically located pods on the terminal inflorescence. Sufficient pollen germination on a stigma did not guarantee full seed set and even when pollen tubes were present at the micropyle regions, ovules were not penetrated. Some seeds aborted: in some, triple fusion did not take place while other seeds were small and deemed at disadvantage to compete for available nutrients.