Krasnovskyi S. Breeding value of corn inbred lines as a component of cold tolerance high yielding hybrids.

Dissertation represent the results of evaluation corn inbred lines and hybrids on cold tolerance and the main economical, agricultural characteristics. Character of cold tolerance inheritance, combining ability of "cold tolerance" and "yield" were determined. Model of cold tolerant inbred line was developed for further applying in breeding process. Effectiveness of cold test method using for selection cold tolerant genotypes was proved. This method recommended for using during first stages of genotype evaluation. 7 cold tolerant inbred lines: Co 255, HLG 1203, HLG 1238, UCH 37, Q 170, Ak 135, FV 243 were selected by using this method. These lines recommended for using as a source of cold tolerance during breeding of cold tolerant hybrids. Created hybrids from this lines show high cold tolerance and yield. Hybrids which showed the highest yield: Co 255/FV 243 - 8,8 t/ha, L 155/Co 255 - 8,3 t/ha, P 165/Co 255 - 8,1 t/ha, L 155/UCH 37 - 8,0 t/ha, and exceed standards on 1,2-2,0 t/ha, recommended for using in further investigation and to apply in industry. Created model of cold tolerant corn line, which include parameters of field and laboratory analyses, sum of effective temperature, combining ability and yield recommended for using during evaluation and selection cold tolerant breeding material.