PHOTOSYNTHETIC AND SEED PRODUCTIVITY OF SOYBEAN DEPENDS ON INOCULATION AND FERTILIZING IN THE CONDITIONS OF RIGHT-BANK FOREST STEPPE
Authors: Furman V. , Furman О. , Svystunova I. 
Published: February 2023

At the current stage of world agricultural production development, soy occupies the leading place among the most critical high-protein and oil crops. Ukraine is the leader in soybean production on the Eurasian continent, however, the biological yield potential of domestic soybean varieties is not yet sufficiently realized, and therefore there is a need to find ways to increase the productivity of soybean agro phytocoenoses. The basis of the creation of the dry weight of the soybean seed crop, like any agricultural crop, is photosynthesis. The intensity of which reflects plants' reaction to the conditions of growth and development, including the technological model of cultivation. Therefore, studying laws that determine the photosynthesis process productivity is an essential way of managing the level of crop productivity.

The purpose of the research was to establish the influence of seed inoculation by microbial preparation of multifunctional action Phosphonitragin and rates and terms of mineral fertilizers application on photosynthetic and seed productivity formation. Visual, measuring-weighing, calculation, and statistical-mathematical methods of observation and research were used during the research.

Field research was conducted during 2013-2016 at the experimental field of the State Enterprise "DG Salivonkivske" of the Institute of Bioenergy Crops and Sugar Beet of the National Academy of Sciences of Ukraine. The soil of the experimental site is a typical low-humus chernozem. Humus content in the 0-20 cm layer - 4.55%, easily hydrolyzed nitrogen (according to Kornfield) - 154-160 mg/kg of soil, mobile phosphorus (according to Chirikov) - 43-55 mg/kg of soil, exchangeable potassium - 94-106 mg/kg of soil, the pH of the salt extract is 6.7-7.1.

The field experiment was laid according to the scheme: factor A - variety: Vilshanka (early ripening), Suzirya (medium ripening); factor B – pre-sowing seeds treatment: without inoculation, bacterial preparation Phosphonitragin; factor C – mineral fertilizer: without fertilizers (control); P60K60; N15P60K60; N30P60K60; N45P60K60; P60K60 +N15; N15Р60K60 + N15; N30Р60K60 + N15. Phosphorous and potash fertilizers were applied during the main tillage, nitrogen fertilizers were applied in accordance with the scheme of the experiment: for pre-sowing cultivation and extra-feeding of soybean plants in the budding phase. Seed inoculation was carried out by a complex bacterial preparation based on phosphorus-mobilizing microorganisms (B. mucilaginosus) and strains of nodule bacteria (Br. japonicum).

In our research, both soybean varieties were characterized by a high level of leaf surface growth, but the medium-ripe Suzirya variety formed a larger leaf area in all phases of development. The most powerful in terms of size - at the level of 34.3-44.9 thousand m2/ha (variety Vilshanka) and 35.5-46.4 thousand m2/ha (variety Suzirya) - the leaf surface in soybean crops was formed in the phase of seeds swelling. The growth of the maximum leaf area was ensured by the combined action of the inoculant and mineral fertilizers in a dose of N30P60K60 + N15 – 44.9-46.4 thousand m2/ha.

The highest content of chlorophyll pigments was noted for the retail application of nitrogen fertilizers - N30 in pre-sowing cultivation on the background of P60K60 and N15 in extra-feeding the budding phase. Compared with a single application of the same amount of nitrogen fertilizers sum of chlorophyll "a" and "c" content was increased by 0.26-0.30 mg/g of raw mass. Bacterization of soybean seeds by Phosphonitragin increased the content of chlorophylls a+b by 20.0-23.1%.

Improvement of nutrition conditions due to the introduction of mineral fertilizers and seeds bacterization by Phosphonitragin had a positive effect on the formation of the net productivity of photosynthesis. Seed inoculation provided an increase in the dry matter by 20.0-29.1%, application of phosphorus-potassium fertilizers by 16.1-17.7%, complete mineral fertilizer by 22.0-45.0% (Vilshanka variety) and 19.1-44.1% (Suzirya variety), including the retail application of nitrogen fertilizers - by 41.0-45.0 and 37.3-44.1%, respectively. The most productive according to this indicator - at the level of 6.28-7.04 t/ha, were the options where seeds were inoculated by Phosphonitragin and N15-30Р60K60 + N15 was applied in the budding phase. In all years of research, the medium-ripe variety Suzirya formed a higher yield of dry mass. According to the results of the correlation-regression analysis, it was determined that the strength of the relationship between the yield level is significant and closely correlated with dry matter accumulation - the correlation coefficient for the Vilshanka variety is r = 0.957, for the Suzirya variety - r = 0.971.

The main criterion for evaluating the performance of the photosynthetic potential is the yield level. The maximum yield - at the level of 2.86 t/ha (early-ripening variety Vilshanka) and 3.15 t/ha (medium-ripening variety Suzirya) was formed in the areas with the highest photosynthetic productivity. Compared to the absolute control the yield increase in the specified options was 53.9 and 44.6%.