Рroductivity of soybean varieties in the inoculation of seeds by nodule and endophytic bacteria in the conditions of irrigation of South of Ukraine
Authors: Goloborodko S. P. , Iutinskaya G. O. , Tytova L. V. , Dubinska O. D. 
Published: July 2020

Formulation of the problem. Soybeans as leguminous crops in the structure of Ukrainian cultivated area, has started to occupy one of the leading places in recent years due to the high content of protein - up to 38-42%, fat - up to 18-23% and carbohydrates - up to 25- 30% in its seeds. One of the most effective ways to increase the soybean seed productivity is the use of environmentally friendly inoculants created on the basis of nodules bacteria.

Analysis of the recent researches and publications. According to the results of scientific researches, conducted in different natural and climatic zones of Ukraine, inoculation of soybean seeds with nodules bacteria significantly increases the symbiotic fixation of molecular nitrogen from air and, consequently the crop yield. It was established that endophytic bacteria along with the nodules bacteria are able to form a powerful symbiotic apparatus on the roots, synthesize biologically active metabolites characterized by antimicrobial action on phytopathogens, or are inducers of systemic plant resistance preventing them from the disease development.

Tasks and methods of the research. The aim of the scientific research was to establish the effect of complex seed inoculation  with the new endophytic bacteria strains along with the nodules bacteria on the formation of crops and the quality of soybean in different varieties of maturing under irrigation conditions in the south of Ukraine. The two-factor field experiment was carried out using the method of split plots, where the main plots (first-order plots, factor A) were the ultra-maturing (Diona) and mid-early (Aratta) soybean varieties. Second-order plots (subdivisions, factor B) were the options for pre-sowing seed treatment: 1 - Check 1 (without seed treatment); 2 - Check 2 (treatment of seeds with water); 3 - RizobinK (association of 3 strains of Bradyrhizobium japonicum UKM B-6018, UKM B-6023, UKM B-6035); 4 - RizobinK + Paenibacillus sp.1; 5 - RisobinK + Bacillus sp.4; 6 - RizobinK + Brevibacillus sp.5; 7 - RhizobinK + Pseudomonas brassicacearum 6; 8 - RizobinK + B. megaterium UKM B-5724.

Presentation of the main material. The total evaporation and total water consumption of soybean varieties different in maturing were determined by a water balance method based on the moisture content of the soil at the beginning and at the end of growing season, use of water for crop formation in the interphase periods and during the whole growing season, taking into account rainfall and irrigation. Generally, the total water consumption of the ultra-maturing soybean variety Diona reached 5102 m3/ha from 0-70 cm of soil layer, and respectively, of the Aratta variety – 5832 m3/ha during the growing season. Pre-sowing inoculation of soybean seeds of different maturing varieties with nodules and endophytic bacteria contributed to the formation of more number of beans on plants and seeds in one bean. The maximum yield of the Diona variety that was obtained by pre-sowing inoculation of seeds with RizobinK + Bacillus sp.4 was 3.19 t/ha, and respectively, of the Aratta variety – 2.75 t/ha. The maximum protein content  of 39.06-39.28% was in the seeds of Diona soybean in the variants where pre-sowing inoculation was carried out with the compositions RizobinK + Brevibacillus sp.5 and RizobinK + P. brassicacearum 6, which exceeded the parameters of Check 1 and Check 2 in 1.45-1.67 and 1.66-1.88 times, respectively. The high fat content was obtained in the seeds of the Diona variety by complex inoculation with the compositions RizobinK + Brevibacillus sp.5 and RizobinK + P.brassicacearum 6 (17.65 and 17.83%, respectively) and in the seeds of Aratta for the treatment with the complex inoculants RizobinK + Bacill. sp.4 and RizobinK + Brevibacillus sp.5 (18.62 and 18.84%) against 15.67–15.90% and 15.21–15.38% in the check variants of the respective varieties.

Conclusions and prospects for further research. Pre-sowing inoculation of soybean seed varieties with nodules and endophytic bacteria, in comparison with the check variants, significantly influenced on the formation of the total number of beans on plants and seeds in one bean, which increased the yield of the Diona variety by 0.57–0.87 t/ha and the Aratta variety by 0.32–0.48 t/ha.