| Results and Discussions The results of cytological studies in hexaploid Triticale parental lines and their F1 fatnilies are presented in Tables 1 and 2. It is clearly noted from the tables that Meiosis-II was more irregular than Meiosis-I. Number of univalents, micronuclei, laggards and bridges per cell were frequently occuring in all the stages of Meiosis-II of all the parental lines and hybrids. Whereas, Bacum, Beagle and Mapache the parental lines and the F1 families of Beaver-arm x Bacum and ITYN78,21 x Beaver-arm did not show any cell with irregular cell division in any stage of Meiosis-I. The normal meiotic-I cell division of Bacum, Beagle and Mapache parental lines indicates that these lines are stable to some extent. Whereas, Mapache the parental line, which shows the minimum number of 4, 5 and 6 irregular cells in AII, TII and Tetrads stages of Meiotic-II division, is comparatively more stable than the other parental lines and hybrids. In F1 families, the hybrid of the cross of ITYN78,21 x Beaver-arm showed normal cell division in meiosis-I and the minimum percentage of cells with irregularities in Meiosis-II. This indicates that this combination was better in reductional cell division in comparison to all other hybrids. Whereas, the highest percentage of irregular cells was recorded in the cross of Beagle x Bacum. Table 2 shows that the average number of cells with irregularities in F1 families were approximately double than that of their parental lines in all the stages of cell divisions. Similarly the average number of univalents per cell in Meiosis-I were also approximately double in F1 families with comparison to their parental lines. However, the average number of univalents, micronuclei and bridges per cell in Meiosis-II cell division were more or less same in the parental lines and F1 hybrids. The fact is clear but difficult to explain that why the hybrids between primary strains of hexaploid Triticale have a more irregular meiosis than the parents. However, this increased meiotic irregularity in F1 combinations of hexaploid Triticale may be caused by substitutional differences between the parents and also by homozygosity for different kinds of translocations. The results obtained in this investigations are in agreement with KROLOW (1969 a,b), MERKER (1973), TSUCHIYA (1974), and WEIMARCK (1974-1975) who recorded meiotic disturbances in Triticale and reported a high frequency of irregular meiosis cell division in F1 hybrids than their parents. The results are also in confirmation with HAFIZ et al. (1982) and HAFIZ and LARIK (1984) who reported a number of meiotic irregularities in Triticale. |
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