G. KIKINDONOV and Tz. KIKINDONOV
Agricultural Institute, BG-9700 Shoumen, Bulgaria
KIKINDONOV, G. and Tz. KIKINDONOV, 2003. Tests of spontaneous tetrahaploid lines, used as pollinators in the sugar beet hybrid breeding. Bulg. J. Agric. Sci., 9: 53–57
Object of the research are multigerm sugar beet tetrahaploids (Th), arisen spontaneously during haploid regenerants' doubling. The higher ploidy level is one of the abnormalities, caused by the treatment of haploid plants with colchicine. The aim of the study is to check whether it is possible to stabilize such aberrations into lines and to include them in the breeding schemes.
Laboratorial analyses show a high pollen's viability. The meiosis is regular, and the purity of the obtained tetraploid level remains completely the same keeping the necessary spatial isolation. The sowing qualities of the seed generation are improved with the lines' stabilization.
In field trials the Th lines demonstrate a high level of the qualitative indices with well expressed morphological uniformity. Tetrahaploids 49 and 55 show a higher resistance to powdery mildew and cercosporose. All the test-crosses of the tetrahaploid lines with the monogerm MS line 19–30 exceed the Standard regarding the sugar content and the output. The crosses with the MS analog of the monogerm dihaploid line 19–66 are more productive than the Standard. Approved higher white sugar yield is formed by the hybrids of the Th pollinators 55 and 49. The increased resistance towards the fungal diseases of tetrahaploids 49 and 55 is inherrited in their hybrids.