Purpose. To analyze the divergence of early maturing source material of corn Zea mays L. in heterosis breeding for the genetic base formation at the State Institution the Institute of Grain Crops of the NAAS of Ukraine. Methods. Field (comprehensive assessment of morphobiological and economically valuable characteristics of the source material and maize hybrids) individual selection, cumulative and recurrent selection, backross and testcrosses bree­ding methods; laboratory; analysis and synthesis; statistical. Results. The results of research on the analysis of the divergence of early maturing corn source material in the conditions of the Steppe of Ukraine has become a developed harmonized working collection of corn breeding samples adapted to the stressful conditions of this region. The gradual cyclical improvement of the lines made it possible to form the core of the genetic diversity of FAO 150–290 early maturing specimens of the southern ecotype, which are competitive in heterosis breeding. The complexity of breeding for early maturity in the steppe conditions is due to the lack of material adapted to the stress factors of the South of Ukraine. The available early maturing lines of the world collection F2, F7, Ер1, Ма21, Ма23, Со125, Со255, См7, PLS61, S72, etc., were distinguished by high cold resistance, good starting plant development, intensive accumulation of dry matter during ripening, but not adapted to the deficiency of moisture in the soil and high summer temperatures. According to the results of the experiment, it was revealed that, in terms of breeding, lines of Lancaster plasma (DK427 and DK633) were the most plastic, due to which a number of new mid-early lines were obtained, for example DK2/427, DK267, DK266/417, DK633/266, DK296, etc., which were included in the registered hybrids. Formation of the genetic base of early maturing maize source material for heterosis breeding and systematization accor­ding to different breeding characteristics provided a balance of samples of alternative components, which will be further used to model heterosis hybrids in the early maturing group. Conclusions. The updated basic collection of lines is represented by the samples of plasma Iodent: DK744SVZM, DK216SVZM, DK4173SVZM, DK235zS, DK257zM, SV, DK365SVZM, DK777ZMSV, DK733-7zM,SV, DK315SVZM; Lancaster: DK296zS,VM, DK633/266zS,VM, DK2965ZSZM, DK2953 ZSZM, DK3023 ZSZM, DK236zS,ZM; Raid (SSS): DK232MV, DK2323MV, DK239MV; Mixed: DK253ZSZM, DK273MV, DK272zS, DK281SV, DK233zM,SV, DK959MV, DK9527 ZSZM, DK247MV, DK2442MV, which is the basis of the genetic diversity of early ripening corn samples included in the State register of plant varie­ties suitable for dissemination in Ukraine.

Purpose. To select promising high productive maize hyb­rids of middle-early maturity group in terms of stability and plasticity of main economic characters. Methods. Field study, laboratory test, analytical procedure and statistical evaluation. Results. 14 maize hybrids recorded in the State Register of Plant Varieties Suitable for Dissemination in Ukraine in 2015 were studied for plasticity and stability of such traits as productivity, protein and starch content. Intensive highly-plastic hybrid ‘SI Tiptop’ was selected among the studied ones for productivity trait that can respond properly to changes of growing conditions. It was defined that for the starch content such hybrids as ‘SI Tiptop’, ‘SI Enigma’, ‘SI Arioso’, ‘Svich 38’, ‘Svich 35’, ‘HU 8653’, ‘Zdobutok’ and ‘SI Contrakt’ belonged to the intensive type and combined rather high values and the stability of the studied trait under variable conditions. The following hybrids as ‘NS 2642’, ‘DK S3016’, ‘Svich 38’, ‘NS 2632’ were qualified as intensive for protein content and appeared to be highly-plastic but stability values of this trait were low. ‘Svich 38’ hybrid was intensive simultaneously for two traits such as protein and starch content and showed rather high values of plasticity. ‘SI Tiptop’, ‘SI Enigma’ and ‘Svich 35’ were defined as hybrids of extensive type that provided stable protein content in adverse cultivation conditions. Conclusions. On the condition that intensive crop growing technologies should be used, for obtaining stable yields it is advisable to sow only highly-plastic hybrids that can adapt to unfavorable environmental factors, including ‘SI Tiptop’ – for productivity trait, ‘Zdobutok’ and ‘SI Kontrakt’ – for starch content, ‘MAC 24N‘, ‘NA 2642‘ and ‘Danubio’ – for protein content.

The results of evaluation and selection of breeding material of mixed germ-plasm corn for early ripeness among self-pollinated families S4 by the length of the «sprouting–flowering of 50% of ears» period are given. A signifi cant infl uence of weather conditions during the years of study on the length of this indicator was determined. Response of studied corn test-crosses on growing conditions are described. Self-pollinated families DK22282111, DK28211111, DK21511111, DK20192321, DK26143111 were singled out which had a high tolerance to growing conditions and stable «sprouting–flowering of 50% of ears» period.

Methodological rationale is given (procedure - morphological description) for ‘plant’ as a quantitative characteristic - ‘plant: ratio of upper ear attachment height to plant height’ for maize hybrids (Zea mays L.), as well as parameters of grading for states of expression are set to facilitate the assessment at performing morphological description of maize hybrids

The article provides methodological ground (method of morphological description) for identification of qualitative, quantitative and pseudo-qualitative characteristics of maize hybrids (Zea mays L) disclosing methodological facets of practical appliance for histogram and variation curve of morphological characteristics of the phenotype by uniformity test and unveiling the link between quantitative characteristics of the ear and economically valuable indices of plant productivity. Target of the research has covered physiological and biochemical processes of plant productivity development into relevant phenological growth and development stages followed by relevant observations and records of vegetative and generative organs of maize. The field examination results obtained are processed with mathematical and statistical methods with the view of searching for margins (min and max) of confidence intervals and in order to verify reliability of the research results with the view of follow-up construction of histogram and variation curve.

In the Forest Steppe Zone of Ukraine studied 6 sorts and 3 hybrids of sweet com. According with results of research work the author came to the conclusion that sorts and hybrids distinguished some economic- important characteristics.

Purpose. Provide bioinformatic analysis and comparison of target regions of the acetolactate synthase (als) gene in several members of the Poaceae family and, on the basis of the obtained data, explore the possibility of creating a unified genetic construct for als gene editing using the CRISPR-Cas9 system. Methods. The als gene sequences of various members of the Poaceae family were obtained from the NCBI: Nucleotide database. For comparison, a fragment of the imi-2 gene of wheat of the soft line ‘TealIMI11A’ was used in two regions of the 367–390 and 1729–1749 nucleotide sequences. The Sequence Viewer 3.37.0 tool was used to assess the presence of nucleotide substitutions in the working sequence of the imi-2 gene. The dendrogram was built using the “Blast Tree” tool from the NCBI: Blast: Nucleotide resource. Results. A comparative analysis of the nucleotide sequences of seven different species was carried out: soft wheat (Triticum aestivum L.), common wild oat (Avena fatua L.), barley (Hordeum vulgare L.), Asian rice (Oryza sativa L.), maize (Zea mays L.), aleppo grass (Sorghum halepense Pers.) and Tausch’s goatgrass (Aegilops tauschii Coss.). The dendrogram is based on the gene sequence als, showed that all studied genotypes can be divided into two blocks: the first block included maize and aleppo grass, and the second block, a separate branch includes Asian rice and common wild oat, barley, soft wheat and Tausch’s goatgrass. 367–390 nucleotide sequences of soft wheat showed the highest 100% homology to Asian rice, Tausch’s goatgrass and common wild oat. The lowest homo­logy was for maize and aleppo grass at 83.3%. Evaluation of the nucleotide sequence 1729–1749 showed no complete homology at the 100% level. It was the highest for barley and Tausch’s goatgrass – 95.2%, and the lowest for rice, maize and aleppo grass – 80.9% each. Conclusions. The analysis confirms a significant degree of homology of the als gene sequence for various species of the Poaceae family, which allows us to create a universal genetic vector. However, taking into account the high degree of sequence homology for species such as soft wheat, Tausch’s goatgrass, barley, Asian rice and common wild oat, it can be assumed that the corresponding genetic vector can be used with the greatest efficiency to alter the als gene of these genotypes.

The article explains the aim and objectives of parental components of maize hybrids identification in the course of soil varietal control. Scientific background has been provided to methodological aspects of comparative evaluation of morphological characteristics on control plots for the purpose of establishing authenticity of maize hybrids circulated at the market.

Purpose. Assessment and selection of self-pollinated S5 maize (Zea mays L.) families with high combining ability and wide adaptive capacity obtained on the basis of specially produced hybrids by crossing elite lines of various genetic plasms with the best main agronomic characters. Methods. Field studies, mathematico-statistical evaluation. Results. An amplitude of grain yield ranging from 5.96–10.96 t/ha (x = 8.44 t/ha) in 2013 to 2.67–7.59 t/ha (x = 5.08 t/ha) in 2014 was determined in the course of study of the testcrosses of self-pollinated S5 families. It was found that different response of genotypes of the studied testcrosses to the year conditions significantly affected the average yield level, which decreased in the stressful 2014 by 3.4 t/ha as compared to 2013. The results of the assessment based on the general and specific combining ability of new parent material of mixed germplasm were shown. A significant variability of the estimates of GCA (general combining ability) effects depending on the year conditions was observed in the course of study. A marked difference in the estimates of GCA effects based on the grain yield was revealed. They were persistently high in 19% of the best self-pollinated families in both years, 14% of the families had persistently low estimates of GCA effects, 67% changed their value depending on the genotype and year conditions. Conclusions. 17 best self-pollinated families with persistently high estimates of GCA, 6 families featuring high tolerance to drought and 4 families with persistently high variances of SCA were selected. The selected families will be used as a parent material in selection programs aimed to create new high performance hybrids.

The results of studies on the major agronomic traits of the best com hybrids of different maturity groups on their suitability to grow in south-western part of the forest- steppe. Use in production practice the proper Selection of hybrids of maize provides an opportunity not only to predict the volume of its production, but also significantly save energy at the post-harvest handling of grains of this crop.