Avena magna is a new tetraploid species morphologically similar to the hexaploid A. sterilis, having a high concentration of protein, large caryopses, and outstanding resistance to crown rust. One genome in A. magna appears homologous to the As genome present in hexaploid, tetraploid, and one group of diploid species. Avena magna is a possible ancestor of cultivated oats.

Diploid Avena strigosa Schreb. and A. wiestii Steud., tetraploid A. abyssinica Hochst., and hexaploid A. sativa L. and A. sterilis L. were cross‐compatible with A. magna Murphy and Tcrrell All hybrids except the pentaploids were sterile. Partial homology of the A genome of the diploid species with one genome of A, magna was indicated by the chromosome associations observed in the triploid hybrids A. magna ✕ A. wiestii and A. strigosa ✕ A. magna. In the tetraploid hybrid, A. abyssinica ✕ A. magna, chromosome associations suggest that the two species have one or both genomes partially common. In the pentaploid hybrids, the frequencies and kinds of chromosome associations observed suggest that A. magna may have two genomes partially in common with two genomes of the hexaploid species, a common genome and the remaining genomes partially common, or two genomes partially in common with the three genomes of the hexaploids.

No abstract

Synopsis Grey‐striped seed color of the CD 3820 parent was dominant to the white color of the CI 4748 parent and conditioned by a single factor. Resistance to 4 races of stem rust and 2 races of crown rust was apparently conditioned by the same gene or genes. Both parents and the F3 population were resistant to race 276 of crown rust.

The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. UMI UMI Microform DP13566