| Résumé | Barbing of awn, carliness of heading, height of plant and disease reaction were investigated in reciprocal crosses between Glabron and Trebi. Barbing of awn was also studied in reciprocal crosses between Velvet and Trebi. Rough-, intermediate- and smooth-awned plants were obtained in the ratio of 12:3:1 in the F2. F3 studies confirmed the F2 findings that two factors, explained on the basis of epistasis, governed barbing of awns. The inheritance of the characters, earliness of heading and height of plant could best be explained by assuming polymeric factors. Both these characters were greatly influenced by the environment. In the genetic studies of stripe reaction Trebi proved highly resistant, and Glabron moderately resistant, while the progeny of the cross between them generally resembled the Trebi parent. No evidence of transgressive reaction for greater resistance was shown. The results indicate that the method of floral inoculation used was not altogether satisfactory. A small positive correlation was found between percentage stripe infection and mean height of plant, whereas no significant correlation was disclosed between stripe reaction and either mean number of days from emergence to heading or barbing of awns. A high degree of association was found between mean height of plant and mean number of days from emergence to heading. The status of the loose smut disease of barley in relation to the breeding of new resistant smooth-awned varieties is discussed. |
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