The assimilation surface of winter wheat under the effect of seed treatment with biological preparations
Authors: Kalenska S. M. , Hordyna O. Yu. 
Published: September 2023

Purpose. To establish the peculiarities of the winter wheat assimilation apparatus development under the effect of seed treatment with biological preparations.

Methods. Research was conducted using field, laboratory and mathematical methods in 2019–2022 in the stationary crop rotation of the Department of Crop Production of the National Academy of Sciences of Ukraine on typical podzolized chernozems in the Right Bank Forest Steppe of Ukraine. The peculiarities of the formation of the assimilation area of winter wheat under the application of biological preparations for seed treatment were studied with the use of the following preparations: Binok Zerno, Rizomax, Trichodermin, Planoriz, Urozhai Start. N32P32K32 fertilizer and complex granular fertilizer DuraSOP actibition were applied in seedbed preparation. The leaf area and glumes were calculated using the Petiole Pro program. The area of the stem was determined by the formula of the external area of the cylinder.

Results. The flag leaf is quite important for the formation of a high yield of winter wheat, since its loss or damage significantly reduces the flow of photosynthetic assimilates into the plant. In particular, in the earing phase (BBCH 57), on average its area was 7.68 thousand m2/ha and good indicators of the formation of the area of the flag leaf were in the treatments with Binok Zerno and Harvest Start, both separately and in combination. In the next phase of development – flowering (BBCH 65) – the patterns were preserved, although the combination of Binok Zerno in a complex with fertilizer Harvest Start was better – 9.24 thousand m2/ha. A decrease in the total assimilation area was observed as a result of the gradual dying off of the leaves of the lower tiers, a reduction in the possibility of photosynthesis of the flag leaf and a decrease in the area of the ear involved in assimilation. In particular, on average according to the experiment, in the earing phase (BBCH 57), the total assimilation area of winter wheat was 51.9 thousand m2/ha; in the flowering phase (BBCH 65) 51.8 and in the phase of milk grain ripeness (BBCH 75) 29.3 thousand m2/ha. The total area of the assimilation surface in the earing phase (BBCH 57) was the largest for the combined seed treatment with the biological preparation Binok Zerno and the fertilizer Urozhai Start – 61.7 thousand m2/ha. In the future, in the phases of flowering (BBCH 65) and milk ripeness of grain (BBCH 75), the obtained patterns were preserved and the best treatment was the combined application of Binok Zerno and Harvest Start. By the end of the vegetation season, the concentration of the main photopigments in the leaves of winter wheat decreased In the phase of milk ripeness of the grain (BBCH 75), the content of chlorophyll a was 11.01 mg/g and chlorophyll b 3.93 mg/g. However, at earlier stages of wheat ontogenesis, the content of chlorophyll b in leaves increased, while chlorophyll a per gram of leaf dry matter decreased. It was established that the average content of chlorophyll a was 11.6 mg/g during the earing phase (BBCH 57), while the content of chlorophyll b was 4.09 mg/ha. In the flowering phase (BBCH 65), their content was 11,4 and 4.14 mg/ha, respectively. It was determined that the complex seed treatment with Binok Zerno + Harvest Start together with fertilizer N32P32K32 + Actibion ensured a higher content of chlorophylls – 16.3; 16.0 and 15.4 mg/g of dry matter, respectively.

Conclusions. The application of the studied biological preparations for the seed treatment of winter wheat seeds contributes to a significant increase of the indicators of the total assimilation area of plants throughout the vegetation season, in particular its components, such as the area of flag leaves, blumes and stems, as well as the content of photosynthetic pigments. Established regularities of plant growth and development are important factors for optimizing crop cultivation technology in the conditions of the Right Bank Forest Steppe of Ukraine.