Nedil's'ka U. Introgression of factors of resistance against dry rot of wild, cultured species to mitial material of potato

The thesis presents results of experiments with the development of initial breebing material which is characterized with a high degree of resistance against dry Fusarium rot and of other agronomic characters. Elements of methods of evaluation of resistance of potato samples against, the disease with the use of artiifial inoculation of tubers were worhed out. Optimal tim for inoculation is the beginning of March. The varieties Polyana, Povin, Slovyanka are considerably better for inoculume accumulation. Wild potato species with a high phenotypic manifestation of resistance against dry rot were determined, viz: S.catarthrum, S.chacoense, S.verrucosum, S.simplicifolium, and especially S.jamesii, S.vernei, S.polytrichom, and also a culti-vated variety - S.andigenum. Polymorphism of species concerning manifestation of the character was established and hence, for the creation of the trait sources, homozy - goti-zathon of valuable allel and congruent crossings were recommended.Possibility of introgression ofeffective genes of the control of the leading trait of wild and cultivated specil into primary, secondary species hybrids and also into material of single crossing of the forns obtained with varieties was proved.Among backcrosses wohich were obtained earlier, the backcrosses were found with high resistance against the disease - up to 8,7 points which was 1,6 times higher fhan the index found in the best standard variety. Efficiency of the genetic control of the character in this material was established. A number of backcrosses combined high re-sistance against dry rot with similar high manifestation of other agronomic characters. Offsprings of crossings of the disease resistant backcrosses, selected for the com-plex of agronomic characters, are characterized not only by a high degree of the beabing trait (75,9 % are more resistant than the best standart variety) but alse by other agro-nomic valuable characters - more than a halt of the material analyzed (51,8 %) had higher yields with early harvesting than the early variety Nezabudka, with the average mass of marketable tubers amaunting to 118 g and starch content - up to 20%. The number of tubers per potato plant amounts to 20 pieces. The selected baskcrosses are promising for the use in practical breeding practice.