| Results The results are presented in Table 1. Meiosis in wheat was very regular with 21 bivalents in the control as well as in most of the treated material. Chiasma frequency displayed decrease after the treatments, except in diakinesis, where it showed significant increase. The separation in the anaphase was normal in the control and after 1.5KR, whereas some irregularities, as lagging univalents and bridges, were observed after 6KR. In general wheat was less radiosensitive. The hexaploid triticale showed 42 chromosomes with 2 rye and 4 wheat genomes. The tetraploid wheat usually forms 14 bivalents, the same behaviour was expected in the hexaploid triticale, however with additional 7 rye bivalents. In accordance with this expectation, 21 bivalents were established in the control of the present material, though a small frequency of univalents and multivalents appeared in metaphase I. Although the frequency of multivalents was very small in the treated material, yet 6KR dose seems to have increased the frequency of univalents. However, a nonsignificant decrease in the chiasma frequency was observed after 6KR dose. In spite of normal chromosome pairing at diakinesis, a high number of meiotic irregularities was typical for the triticale. Disturbances were observed at all stages of miosis: in M1 chromosomes outside the equatorial plate; in AI and AII, lagging chromosemes and sometimes bridges in telophases and in tetrads many micronuclei, in addition to that polyads were also observed. Furthermore, as it could be seen from Table 1 the meiotic irregularities increased with the increase in dose. In number of micronuclei and lagging chromosome there was a significant difference between the control and the treated population after 1.5KR and 6KR. The main conclusion is that triticale is more radiosensitive than wheat. In rye, the meiotic studies comprised the 1.5KR treatment besides the control. Pairing at diakinesis was normal, 7 bivalents in the control and 6.9 in the treated population, a difference which is not significant. In the metaphase however, configurations other than bivalents were observed. There was a highly significant difference between the control and the treated material regarding the frequency of univalents and bivalents. A slight and nonsignificant decrease in the number of chiasmata occurred in the treated material at diakinesis and metaphase. Anaphase separation was normal in control, but some irregularies like dicentric bridges with or without acentric fragments, were observed at anaphase or telophase. Lagging univalents were also observed in the treated population. The frequency of bridges and fragments in same cells as well as the frequency of bridges was higher in the treated material than the control, only the latter being significant. In general the rye material was more affected than the wheat after the same dose. |
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