Grapevine breeding by gamma radiation: results and prospects

A method to induce mutations by gamma radiation treatment in 5 cultivars of grape is described. The treatment increased variability in the comparatively small population allowing the selection of some interesting mutants. In 'Dolcetto', which shows a tendency to berry drop, no dropping mutants were found as well as some early ripening plants. Polyploidy, resulting in big berries with a better resistance to Botrytis cinerea, was obtained in 'Barbera'. A 'Delight' mutant was selected for berry size that was bigger than in the control. Cases of seedlessness were found in 'Queen of vineyards'; berries were sweet and juicy but small sized. Negative mutations were found: reduction of fertility and very small berries, and types with pigmentation defects in the leaves. (author)