Potential seed multiplication problems arising from the existence of two genes for the absence of tannin in Vicia faba L.

The presence of two different genes for the white flower character (zt1 and zt2) (pleiotropic with the absence of tannin) in Vicia faba L., which, whe n cross-pollinated, produce coloured flowered plants containing tannin has been known for some time. Recent results have highlighted agronomic, feedin g and nutritional differences between varieties carrying either of the two genes for zero tannin. Current experience has identified possible problems that could arise in seed craps as a result of uncontrolled cross-pollinatio n between them. Now that present day varieties in commerce carry either of the two genes, it is considered useful to list the varieties where the gene s are known, in order to help breeders decide which varieties to use in bre eding programmes and seed multipliers to adapt isolation distances.