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Chromosome variations in some strains of hexaploid
Triticale1) T. TSUCHIYA Department of Plant Science, University of Manitoba, Winnipeg, Canada Chromosome numbers in eight strains of hexaploid Triticale were studied, the materials being shown in Table 1. Most of the materials have been grown 7 or 8 generations after the crosses were made between different lines of primary Triticale (Table 1). Chromosome numbers were counted in root tip cells. The results of chromosome counts in bulk population were shown in Table 2. Chromosome numbers varied from 2n=40 to 44 with the exceptions of each one of 2n=21 and 63. The frequency of 42-chromosome plants varied from the lowest 85.1 percent to the highest 90.1 percent, the overall average for eight strains was 88.5 percent. The differences of the frequency of euploids between groups, between lines within group, and between any two lines were not statistically significant. The frequency of hypoploids (7.7% On an average) was higher than hyperploids (3.8% on an average). Four out of 818 plants (0.49%) had telocentric chromosomes. The 42-chromosome plants from the above bulk populations were grown in the greenhouse and the chromosome numbers were studied in the progeny of those 42-chromosome plants with the results shown in Table 3. Chromosome numbers varied from 2n=39 to 43. Telocentric chromosome was found in three out of a total 674 plants (0.45%) studied, which is similar to the value in the bulk population (0.49%). The cytological stability expressed by the frequency of 42-chromosome plants varied from the lowest 83.0 to the highest 98.5 percent, the overall average frequency for eight lines being 90.4 percent which is not significantly different from that of bulk population. There are no differences in the frequency of 42-chromosome plants between different lines within each group. The difference of the cytological stability between groups A and B, and B and C was statistically significant, group B being shown highest average stability with 96.9 percent of 42-chromosome plants. The difference between the group A and C was not significant. The frequency of hypoploids are higher (8.2%) than that of hyperploids (1.5%). It is noteworthy here that no hyperploid was obtained in either strain of the group B. (Received March 4, 1968) |
| 1) This work was supported by a Research Grant from the Rockefeller Foundation (RF 65019). |