Formation of individual productivity of winter durum wheat by its structural components depending on the fertilizer system

Abstract

The individual productivity of winter durum wheat varies signifcantly depending on the fertilizer system in crop rotation, the effectiveness of which is determined by the weather conditions of the growing season. Stem density, tillering coefcients increase signifcantly due to the application of complete fertilizer. Variants of the experiment with incomplete return of phosphorus and potassium removed with crops do not signifcantly affect the structure of the crop. The amount of productive stems increased from 291 pcs/m2 in the version without fertilizers to 338 pcs/m2 or by 16 % for prolonged use of N75 in feld crop rotation and to 397 pcs/ m2, or by 36 % for N150. In the version with prolonged use of N75P30K40, this fgure was 19 %, and with the application of N150P60K80 – 43 % higher compared to unfertilized sites. Prolonged use of nitrogen-potassium and nitrogen-phosphorus fertilizer system in terms of the impact on the structure of the crop was at the level of the N150 application option. The number of productive stems in versions with incomplete return to the soil of phosphorus and potassium removed with crops was at the level of the variant with complete fertilizer (N150P30K40). The highest tillering coefcient was in the phase of plants entering the tube – 2.00–2.07, and by the end of the growing season it was decreasing. The lowest coefcient of productive tillering was at fully ripe stage of grain – 1.09–0.54 depending on the fertilizer system. The tendency to influence this indicator was similar to the density of stems. Application of 75 kg a.i./ha of nitrogen fertilizers increases the weight of grains and their number per ear. Increasing their dose up to 150 kg a.i./ha reduces the productivity of the ear. The weight of 1000 grains decreases for all fertilizer systems in crop rotation, but remains very high (≥ 35 g). On average over two years of research it was found that the weight of grain from one ear increased from 1.51 g in the version without fertilizers to 1.63 g or by 8 % with prolonged use of N75, and decreased to 1.45 g, or by 4 % in the version of application of 150 kg a.i./ha of nitrogen fertilizers. Prolonged use of N75P30K40 did not affect this fgure compared to the option of applying only 75 kg a.i./ ha of nitrogen fertilizers. In the N150P60K80 version, the grain weight from one ear was at the control level. The weight of 1000 grains of winter durum wheat in unfertilized sites was 43.0 g, and with the application of nitrogen fertilizers was 41.0–41.7 g. In 2020, the weight of 1000 grains was larger and made 41.5–43.3 g, while in 2021 – 40.3–42.6 g, depending on the version of the experiment. Grain yield was most affected by the nitrogen component in the fertilizer system. Key words: winter durum wheat, fertilizer systems, components of crop structure, stability index.