| Polyhaploids of Triticale E. SANCHEZ-MONGE Estacion Experimental de Aula Dei, Zaragoza, Spain With the purpose of comparing the ecological behaviour of our 42-chromosome Triticale with 56-chromosome forms under Spanish conditions, crosses have been carried out between Mediterranean common wheat varieties and rye. From 100 pollinated flowers in one of these cross-combinations, 26 F1 plants were obtained, of which 20 produced partially fertile ears after colchicine treatment in 1955. The seeds from these plants were sown separately. The severe winter of 1955-1956 eliminated 6 of the 20 plant progenies. Of the 14 progenies coming into maturity an analysis of the fertility is given in Table 1. A study of the meiosis in the PMC of several plants of each progeny, fixed at random, showed that 13 progenies have 56 chromosomes, while progeny No. 65, comprising 9 plants, revealed some deviating chromosome numbers, which compelled us to study more closely all 9 plants. Chromosome counts in the root tips of these plants gave the following results: 5 plants having 2n=56, 1 Plant with 2n=40 and 3 plants with 2n=28. The meiotic behaviour in the PMC of the plants with 2n=28 is summarized in Table 2. The plants with 2n=28 are obviously polyhaploids having 21 chromosomes of Triticum aestivum and 7 of Secale cereale. Polyhaploids derived from artificial amphidiploids have been reported before (cf. D. Kostoff 1942, Bibliographia Genetica 13 : 1-148) and are in most cases due to pollination with foreign pollen. But cases have been also reported where haploids have been induced either by delayed pollination or by pollination with irradiated pollen. As our polyhaploid plants were grown from seeds obtained from a partially fertile ear, lack of pollen or its bad quality may be the cause of their parthenogenetic origin. (Received March 28, 1957) |