1. Cytogenetical researches were carried on the F
1 plants raised between
T. orientale×
S. africanum (ToriSaF
1) and
T. Spelta×S. montanum (TSpeSmF
1). 2. The percentage of the matured F
1 plants to the number of pollinated flowers in these hybrids were 0.87 and 1.38 percent respectively. 3. The external characteristics of ToriSaF
1 plants resembled somewhat to the pollen plant, while TSpeSmF
1 to the mother plant than being the intermediate of both parents (photos. 1-2, Table 2) in both cases. 4. ToriSaF
1 plant showed fertility, while TSpeSmF
1 was completely sterile (Table 2). 5. In the 2 F
1 hybrids, the number of bivalents at heterotypic metaphase of PMC's is given in Table 3 and 5. 6. The number of bivalents, for ToriSaF
1 up to 3 and for TSpeSmF
1 up to 7, may be chiefly due to the autosyndesis of chromosomes of AB (ToriSaF
1) or ABD (TSpeSmF
1) genomes. In these bivalents of TSpeSmF
1, however, bivalents produced by conjugation of the chromosomes of
S. montanum may have been involved. 7. In these F
1, the formation of equatorial plate in heterotypic metaphase of PMC's was observed in some individuals, in addition to the normal F
1-type division commonly observed in the wheat-rye F
1 hybrids. The frequency of the formation of equatorial plate is given in Table 4 and 6.
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