The height of attachment of the cob and the number of leaves on the main stem was observed slightly lower, but positive relationship (r = 0.65-0.61). Yield capacity and mass of cob was related by strong positive relation r = 0,74 in 2018 and mediumr = 0,47in 2017. Reliable and stable connections of medium strength were found between the number of days from germination to flowering of cobs and full maturity (r = 0,52-0,77). This proves that in breeding for early ripeness, preference should be given to lines with early periods of flowering cobs. Attention deserve indicator of the height of attachment of the cob, this trait is associated with resistance to lodging of stem and suitability of corn for mechanized harvesting. Literature data points that optimal height of attachment of cob is 50-70 cm. It was established that height of attachment of low cob has significant medium correlation with quantity of leaves on main stem (r = 0,65-0,61) and yield capacity (r = 0,54-0,60).One of important characteristic of yield considers mass of 1000 grains. Conducted research points on presence positive but not significant correlation (on 95% level) and in 2017-2018 reached an average (r = 0,49-0,43) level.It was established that lines which were involved in scheme of dialeal crosses has strong differed from each other both on specific combination ability and it stability in different years. Most stable and high manifestation of specific combination ability on yield capacity provides lines Um 331 and Um 337 that give us possibility to use them as valuable components for creation of single high productive hybrids. Lowest indicators was fixed in Co125 (from -0,58 to -0,79). That is higher or lower value of specific combination ability in largely dependent from genotype of inbred lines and their specific reaction on condition of growing.

In the article it is shown the results of the study of heterosis hybrids of corn on the signs of early ripening, such as: the growing season, the number of leaves on the main stem, the moisture yield of grain during harvest. To distribute our corn material by precocity, a number of studies were conducted, namely: estimating the length of the growing season "shoots – full ripeness", which was determined in days, and a very important indicator today is the moisture content of grain when harvested in percentage, it allowed to distribute heterosis hybrids into two groups: early-maturing (106–114) and middle-early – 114–123 days. Over the years of testing, the weather conditions varied considerably, which made it possible to evaluate in detail the material under study. In 2020, the growing season was within 107.8 days, which is almost three days less than in 2021. At the same time, the longer vegetation period was in 2021. Therefore, the aim of our study was to analyze the rate of moisture yield of corn grain of the studied hybrids of the two maturity groups. The conducted researches allowed to trace the dynamics of grain moisture yield of early-maturing maize hybrids and one hybrid of the middle-ripening group of maturity, to determine the variability of hybrid grain moisture in different periods of grain maturation. The year 2021 was more favorable for growing corn, the plants formed a large vegetative mass, but the grain had a high humidity during the harvest period. This is due to a significant amount of precipitation (69.9 mm) in August 2021. Hybrids that had high harvest humidity were characterized by a long growing season, such as № 47 × № 33. Therefore, our selected hybrids can be successfully used in planning a strategy for early maturity. In establishing the patterns of moisture transfer of grain when it reaches, in particular, the influence of the conditions of the year, in our study group were identified two hybrids consistently better in terms of grain moisture. Preference should be given to hybrids № 31 × № 37 and № 83 × № 125, which combine indicators of early maturity: the shortest growing season, the number of leaves on the main stem and the rate of moisture.

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