Realization of soybean biological potential as affected by agronomical practices under the conditions of the Forest-Steppe of Ukraine

Abstract

Purpose. To identify the productivity formation peculiarities of certain soybean varieties as affected by organic fertilizer, plant growth regulators, and moisture retainer application under the conditions of the Forest-Steppe of Ukraine.

Methods. Soybean varieties ‘Ustia’, ‘Kano’, and ‘Hieba’ served as the object of the study. Moisture retainer ‘Aquasorb’ was introduced a month before sowing soybean in 10-cm strips in the zone of rows at the application rate of 300 kg/ha. Organic fertilizer ‘Parostok’ (mark 20) was applied twice: at the 3–5 leaf stage and at the 9–11 leaf stage. Growth regulators ‘Vermystym D’ and ‘Ahrostymulin’ were applied at the stage of budding at the recommended by producer dose.

Results. The formulations under investigation did not affect the duration of phenological stages, and development of soybean plants occurred in accordance with their varietal characteristics and weather conditions of the year. The vegetation period of the varieties under study ranged from 109 to 117 days, which was typical of a mid-ripe­ning soybean group. Pre-sowing introduction of the moisture retainer ‘Aquasorb’ provided an increase in the soil water storage. As of 20 May 2016, the soil water storage in the 0–20 cm soil layer was 42 mm, while in the treatment with a moisture retainer it was 46 mm; in 2017, the values were 31 and 36 mm, respectively. On average, the plant density (per 1 m²)in ‘Kano’ sowings was 60.6, in ‘Hieba’ 58.5 and in ‘Ustia’ 59.2. The moisture retainer ‘Aquasorb’A provided a significant influence on the plant density formation, while organic fertilizers and growth regulators had almost no effect. The minimum yield of soybean grain in the control treatment (no formulations applied) was as follows: 3.99 t/ha in ‘Kano’, 1.72 t/ha in ‘Hieba’, and 2.43 t/ha in ‘Ustia’. All investigated agronomical practices ensured a significant increase in grain yield. The maximum yield in the experiment (4.74 t/ha) was provided by ‘Kano’ variety in the treatment with the complex application of moisture retainer ‘Aquasorb’, organic fertilizer ‘Parostok’ and growth regulator ‘Vermystym D’. The content of crude protein in soybean seeds in the control treatment varied from 35.2 to 36.6%. Application of the moisture retainer did not have any significant effect on this indicator. Top dressing with fertilizer increased the content of crude protein by 0.2–0.7% in different varieties. The maximum content of crude protein was obtained in the treatment with combined application of organic fertilizer and plant growth regulators.

Conclusions. Integrated application of moisture retainer, organic fertilizer and plant growth regulators in soybean sowings is an important and effective factor in the realization of the crop yield potential. The quantitative and qualitative parameters of the crop productivity formation determined in the research can be used to improve the crop cultivation technology under the conditions of the Forest-Steppe of Ukraine.