MONOSOMICS OF AVENA BYZANTINA C. KOCH. II. BREEDING BEHAVIOR AND MORPHOLOGY

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Abstract
Five monosomic lines resitant to Helminthosporium victoriae were isolated from mutant lines of variety ''Victorgrain'' and studied under controlled environments. In the progenies of selfed monosomics the frequencies of disomics varied from 0 to 3%; monosomics, from 38.7 to 85.1%; nullisomics, from 0 to 61.3%; and other monosomal types from 0 to 17.1%. Germination percentages for different monosomes varied from 84 to 99%. No agreement was found between the expected and observed frequencies of disomics, monosomics, and nullisomics in selfed monosomic progenies in any of the monosomic lines. In the progenies of selfed monosomes the fertilities of the disomics ranged from 92.6 to 100%; monosomics from 82.9 to 90.8%; and nullisomics from 0 to 36.9%. Nullisomic plants in all the monosomic lines were reduced in mean plant height over their disomics or monosomics. The gene(s) for gray lemma and fertility were placed on the short arm of M-3, gene(s) controlling normal leaf width on ST-7, gene(s) for inhibition of fatuoid character, crooked rachis base, and yellowish leaf on the long arm of SM-12 or 13, and gene(s) for normal maturity and green floret base on ST-17. The gene Vb, conferring susceptibility to H. victoriae was not associated with any of the monosomic lines studied.