Abstract
1. F23 plants (Tri F23-20-3-4-5-17) derived from the Triticum-Secale triple hybrids Triticum turgidum×Secale cereale F1×Triticum vulgare were cytogenetically studied.
2. Most of the F23 plants had 42 somatic chromosomes (Fig. 1), though some exceptional plants (6.7% in frequency) had 41.
3. The external characteristics of the F23 plants are shown in Table 1. On the neck of their spikes a cluster of hairs was observed and the spikelet was not brittle at the ripening stage.
4. 42 chromosomes in total were also observed in the heterotypic division of PMC's. At the metaphase plates 17-21 bivalents and 0-8 univalents were observed. Frequency of various meiotic configurations is shown in Table 3, among them 21II appearing to be the mode. The average number of bivalents was 20.56 (Table 3). Ring-shaped bivalents, which are formed by the partners of equal size conjugating at their both ends and found in a pure species, were generally observed. Some stick-shaped bivalents were also observed (Figs. 8, 10).
5. 14 out of the 21 bivalents at MI might have resulted from pairing of chromosomes in A and B genomes which were derived from Triticum turgidum (AB) and/or T. vulgare(ABD).
If all of the remaining 7 bivalents belonged to D genome, the plants would be the same to Triticum vulgare, one of the cross parents. While they would be the same to Triticum turgidum (AB)×Secale cereale (R) amphidiploids, if the all 7 belonged to R genome. Because their external morphology was not same to either T. vulgare or the amphidiploids, the 7 bivalents seem to be a mixture of the gemini derived from D (T. vulgare) and R (S. cereale) genomes. In order to investigate origin of those bivalents it is necessary to carry out a cytological research of the hybrids between the triple F23 and S. cereale, and T. vulgare and (Emmer wheat×S. cereale) amphidiploids.
