Hybrids of Trifolium pratense L. (2n=14+2) wth T.diffusum Ehrh. (2n=16) and other 16 chromosome Trifolium species
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12-chromosome forms of red clover (2n=14+2) were crossed to six Trifolium species with the chromosome number 2n=16.Hybrids plants were derived from the cross of s stable 16-chromosome red clover T.pratense with T.diffusum (2n=16).No seeds were obtained from reciprocal crosses.F1 hybrid lantswere morphologically more similar to T.diffusum, whereas their other characters, e.g. flower number per head, were intermediate between the species crossed.All F1 hybrids had the chromosome number 2n=16.Meiosis proceeded with large irregularities.The average number of bivalents per cell was 3.32, and that of univalents -.98.Univalents exibited a high stickiness and frequently formed "end-to-end" configurations chains consisting of about a dozen of so chromosomes.Bivalents were straight.Lagging chromosomes and chromosomes bridges were observed during AI; lagging chromosomes were also found during AII.After an equalizing division,tetrads and different from them microspore polyads were formed.16-chromosome hybrids were male- and female-sterile.No hybrids were obtained from the stable 16-chromosome red clover T.pratense (n=7 chromosomes) crossed to the selected clover species (T.apertum Bobr., T.alexandrium L. and others) with n=8 chromosomes.
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