Object of research: peculiarities of heterosis selection for early, stress-tolerant genotypes and clarification of their seed production elements. Objective: Theoretical substantiation and practical implementation of methodical approaches set in the corn selection for early hybrids of northern and southern ecotypes with accelerated maturation and grain moisture return, with cost-effective seed production, competitive in modern market conditions.
Methods: general scientific, special (field, laboratory, laboratory-field, experimental-production), mathematical-statistical. Novelty. The formation peculiarities of the early corn lines’ genetic diversity have been established for heterosis selection. The heterosis models of early and middle hybrids that provide the highest economic effect in specific growing conditions are determined. The matroclinal haploidy method has been improved and adapted to obtain double-haploid lines; the selection methodology principles have been developed for selection of own haplo-stimulating genotypes. The climate transformation processes influence on the reduction of the corn growing season length has been proved, which led to an increase in the corn yield during the research period by almost 1 ton / ha. An integrated system for assessing the growing season length has been improved. The alternative method foundations based on SNP analysis have been developed for determining early maturity. The synthesis possibility and hybrids’ estimation is theoretically grounded for the northern ecotype in the steppe zone conditions. Results. Methods of homozygous material accelerated creation were modified and implemented in the selection process - matroclinal haploidy, SNP-markers, MAS-selection. They allow to accelerate the process of commercial hybrids creation and to reduce two or three times the cyclic improvement term of the source material. A unique collection of genotypes of northern and southern ecotypes has been formed, a new methodological paradigm has been developed, the existing methods was adapted and improved regarding the issues of selection materials creation and evaluation rules; on this basis 162 different biotypes and directions of the corn hybrids use were obtained, as well as 165 of their parent components. The degree of implementation. The hybrids have been introduced into the agricultural production in Ukraine, the Republic of Belarus, the Russian Federation, and Kazakhstan. In the last eight years, the area of hybridization land lots was 10-14 thousand hectares, which allowed receiving annually enough F1 seeds to sow on the area of over 1 million hectares. The scientific and methodological developments are included in breeding programs of Plant Production Institute named after V. Ya. Yuryev at NAAS and of Plant Breeding and Genetics Institute – National Center of Seed and Cultivar Investigation. 327 copyright certificates for corn hybrids and their parent components were obtained, as well as 5 patents for utility models and one patent for invention. Scope of implementation: scientific institutions at NAAS of Ukraine and the Ministry of Agriculture of Ukraine, higher educational establishments, agricultural companies of Ukraine, the Republic of Belarus, the Russian Federation, Kazakhstan.
