Genetical and cytological studies in the breeding of amphidiploid types between Triticum and Secale. : VI.B.Meiosis of PMC's T.compactum x S.cereale F₂ plants with 2n=56 and 58 chromosomes.

Abstract

1. In the present report, some results of cytological studies on the meiosis of PMC' s of F₂ plants raised between T. compactum and S. cereale (TCSF2) whose chromosomes are 2n=56 and 58 were descibed. These TcSF₂ plants were obtained 1943. 2. The group having 2n=56 chromosomes : At the heterotypic metaphase in PMC' s of every plant of this group were observed 22-28 bivalents, or 0-12 univalents (Figs. 4-lO). The frequency of bivalents in the PMC' s was shown in Table 1 and the case of 26II and 27IIappeared to be the mode accarding to individuals at the hetero-typic metaphase but no trivalents was found. Haploldic nuclear plates having 7II+14I or 8II +12I chromosomes, were observed (Figs. 18-20). Moreover, a nuclear plate with 14II +14I chromosomes (what may be ca, 1led hyper-haploidic) was sometimes observed in additijon to the haploidic plate (Fig. 21). The distribution of chromosomes to opposite poles at the anaphase in heterotypic division proceeded nearly normally in most cases, viz., a nuclear plate having 28 chromosomes at the homLotypic metaphase was frequently observed. Among TcSF₂ plants, five individuals having 2n= 56 cllromosomes showed fertility, and the fertility for the spikelet has shown to vary from 12. 90-95.55 percent according to the individuals.