| Development of secondary hexaploid Triticales
by crossing Triticale with rye A. KISS and L-ne VIDEKI Agricultural Experimental Institute of Duna-Tiszakoz, Kecskemet, Hungary Under our conditions hexaploid Triticale-forms are more productive than octoploids. Hexaploids, however, incline to lodging, and characteristics concerning earliness, winter-hardiness and drought tolerance do not fill the requirements. These unfavourable qualities must be implicitely improved upon, in order to make them competetive with traditional fodder cereals. Protein content is satisfactory; but the lysine and triptophane content in Triticale protein has to be improved. For food purposes it is important to develop gluten of good quality and to improve the baking and technological qualities. Feeding problems have been caused by spontaneous infections of ergot (Claviceps purpurea). Animals do like it as grain fodder. Its present nutrition value is slightly better than that of wheat or maize. In regions where rye is grown its quality surpasses that of rye-bread. As in Hungary bread made of wheat is preferred, Triticale as bread cerel, is not a primary question. At the present stage of Triticales breeding we have to examine which way to follow in improving and how to enlarge variability. Crossing octoploids with hexaploid Triticales are highly adequate for this purpose. However, when developing secondary hexaploid Triticales the significance of the rye and wheat genome respectively has not been cleared up yet. In the present study the part of the rye genome was examined (Table 1.). In 1966 401 seeds (10.77%) were obtained from crossing 3720 flowers; in 1967, 10 seeds (1.09%) were obtained when crossing 922 flowers, and in 1968 two seeds (0.38%) were obtained from crossing 524 flowers. SULUNDIN and NAUMOVA (1965) obtained seed set of 16.5%, while in 1965-67 TARKOWSKI got 38.8-45.8%. TARKOWSKI doubled the chromosomes in a F1 plant with 28 chromosomes and got a completely new alloautooctoploid plant with genomes AABBSSSS. It is from this plant that he wants to develop a cross pollinating Triticale-form. We had in mind to develop more secondary hexaploid Triticales. Thus, F1 plants when in bloom were backcrossed with Triticale No. 57 and No. 64. While in the first generation of the hexaploid wheat x rye cross flowers are almost entirely sterile (out of 100 flowers 0.2 seeds are expected), FI flowers of the hexaploid Triticale x rye cross are slightly more fertile, since we got an average of 1-2 seed out of a hundred flowers. In extreme cases seed set per plant can vary between 0-112. When examining pollen in the first generation of the hexaploid wheat x rye, stained pollen grains represented 0-19%; in the first generation of hexaploid Triticale x rye the extreme values of stained pollen grams varied between 9.7-51.0%. All this can be explained by differences of the basic genomes. In the wheat rye cross the genome formula of the F1 plants is ABDS, while the hexaploid Triticale x rye cross contains ABSS genomes, that is, beside the AB genomes of wheat there are two rye genomes. In meiosis rye chromosomes segregate normally, while wheat chromosomes form univalents, and it is very seldom that pairing occurs between homoeologous chromosomes (1-21%). |
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