INTERSPECIFIC CROSSES INVOLVING ALFALFA. IL MEDICAGO CANCELLATA M.B. x M. SATIVA L.

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Abstract
M. cancellata, a hexaploid (2n=48) species could be easily crossed with tetraploid (2n=32 M. sativa (sensu lato). The F1 hybrids were pentaploid; the F2 plants derived from them varied in chromosome number (2n=36 to 41) and on intercrossing showed a strongly reduced fertility indicating a blind-alley for further evolutionary development. No hybrids were obtained with diploid M. sativa; only one hypohexaploid plant was secured on intercrossing with hexaploid M. sativa. This (2n=46 plant transmitted a fairly constant chromosome number (2n=46 -47) to its F2, and those did not show any decrease in fertility on intercrossing. Genetic experiments using anthocyanin color in petals as marker-character indicated that interchange of genetic material took place in hybrids at meiosis. Rations obtained, and constancy of chromosome number in hexaploid F2, led to the assumption that M. cancellata at the n-phase had one genome common with M. sativa and two genomes derived from some other species, probably from M. rhodopaea Velen. or closely related to it.