Managed Bee Pollination Enhances Yield and Seed Quality in Brassica napus through Flowering Duration and Agronomic Trait Modulation

Managed bees are widely recognized as beneficial for agricultural production. However, their impacts vary across plant varieties, and the underlying mechanisms for this variation remain poorly understood. In the present study, the effects of bee pollination were investigated in nine Brassica napus varieties were investigated for flowering duration, fruiting duration, agronomic traits, fruit yield, and seed quality. These effects were then compared with those of non-bee pollination treatments. Bee pollination shortened the flowering duration by an average of 7.3 days and extended the fruiting duration by 2.3 days for all varieties. It also induced changes in agronomic traits in a subset of varieties, including reduced plant height and fewer primary and secondary branches. Correlation analysis indicated that a shortened flowering duration was conducive to enhancing both yield and quality. Increased fruiting duration and the total flowering and fruiting duration contributed to increased grain size-related parameters, including 1000-seed weight and number of seeds per silique. Reduced plant height increased yield by increasing the number of siliques (despite a concurrent decrease in 1000-seed weight), whereas significant reductions in branch number led to lower oleic acid and higher erucic acid content. These findings suggest that bee pollination may substantially improve fruit yield and seed quality, potentially by affecting plant nutrient allocation strategies. Notably, the contribution of a shortened flowering duration appears to be more universally applicable. For practical applications, pollination should be implemented before flowering, and varieties exhibiting favorable agronomic trait changes after bee pollination should be prioritized for promotion and cultivation.