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Title: PEAR MUTAGENESIS: IN VITRO TREATMENT WITH GAMMA-RAYS AND FIELD SELECTION FOR PRODUCTIVITY AND FIELD TRAITS.

Author
item PREDIERI, S. - CNR, BOLOGNA, ITALY
item Zimmerman, Richard

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: For modern orchards, it is desirable to have more compact (dwarfed) trees that produce early and consistent high yields. Shoots of six important pear varieties were grown in tissue culture and then exposed to gamma radiation. The shoots were then multiplied and rooted. The resulting trees were planted in two orchards where they were evaluated for 10 years. From these orchards, 97 trees were selected for early fruiting, high yield, consistent production and small tree size. The most promising trees have been propagated and planted in production trials for further evaluation before being released to growers. The information obtained from this study will be used by other scientists, particularly fruit breeders, and by commercial pear growers.

Technical Abstract: In vitro shoots of six pear (Pyrus communis L.) cultivars, 'Conference', 'Doyenne d'Hiver', 'Passe Crassane', 'Bartlett', 'Abbe Fetel' and 'Butirra Precoce Morettini' were irradiated with gamma rays (3.5 Gy). After three subcultures, microcuttings from the irradiated shoots and from additional non-irradiated microcuttings were rooted to establish plants for survey orchards. All trees were individually observed for variation in fruit traits and for productivity. Trees were selected for improved characters related to production such as early bearing and consistent productivity. Variations observed 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 Crassane'. Of the 97 variants selected, only two showed chimeral behavior.