Pear mutagenesis: In vitro treatment with gamma-rays and field selection for productivity and fruit traits

In vitro shoots of six pear (Pyrus communis L.) cultivars, 'Conference', 'D oyenne d'Hiver', 'Passe Crassane', 'Bartlett', 'Abbe Fetel' and 'Butirra Pr ecoce Morettini' were irradiated with gamma rays (3.5 Gy). After three subc ultures, microcuttings from the irradiated shoots and from additional non-i rradiated microcuttings were rooted to establish plants for survey orchards . All trees were individually observed for variation in fruit traits and fo r productivity. Trees were selected for improved characters related to prod uction such as early bearing and consistent productivity. Variations observ ed in fruit appearance concerned degree of russeting, fruit shape and size. The frequencies of the observed variations in fruit traits depended on the cultivar, ranging from 0.81% in 'Doyenne d'Hiver' to 3.64% in 'Passe Crass ane'. Of the 97 variants selected, only two showed chimeral behavior.