| Based on male and female transmission rates, the expected frequencies
of euploids and aneuploids were calculated and compared to the observed
ratio. Observed frequencies of euploid and aneuploid plants were close to
the calculated value. However, it is safe to say that aneuploid gametes
are able to transmit even through the pollen to a considerable high frequency
in hexaploid triticale. This finding is in conflict to the results
reported by PIERITZ (1966) in octoploid strains which showed a strong selection
against abnormal gametes. Further, these results suggest that monosomics
(2n=41) and other hypoploids could be the sources of more aneuploids, particularly
hypoploids in population of hexaploid triticale. From cytological instability represented by the frequency of aneuploids in the euploid population, it is reasonable to assume that these aneuploids have been derived from the fertilization of abnormal gametes resulting from irregular meiosis. The results suggest that screening of euploids is very important and highly desirable in plant breeding and practical cultivation of triticale. For this, critical study of meiosis and routine chromosome counts in each population are necessary in triticale breeding until truely stable strains are established. References KROLOW, K.D. 1966. Z. Pflanzenzucht 55: 105-138. MERKER, A. 1973. Hereditas 74: 1-6. NAKAJIMA, G. 1953. Jap. J. Breeding 2: 178-184. NAKAJIMA, G. 1965. La Kromosomo 61: 1999-2004. PIERITZ, W.J. 1966. Z. Pflanzenzucht 56: 27-69. TSUCHIYA, T. 1969. wheat Newsletter 15: 10-17. TSUCHIYA, T. 1973. Euphytica 22: 592-599. TSUCHIYA, T. 1974. Triticale: First Man-Made Cereal. p 62-89. TSUCHIYA, T. and E.N. LARTER. 1969. Wheat Inf. Serv. 28: 16-18. TSUCHIYA, T. and E.N. LARTER. 1971. Euphytica 20: 591-596. |
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