Formation of Sorghum vulgare and Sorghum orysoidum productivity as affected by sowing dates in the conditions of the eastern part of the Forest-Steppe of Ukraine

Abstract

Purpose. To investigate the influence of varietal characteristics and terms of sowing seeds on the productivity of Sorghum vulgare and Sorghum orysoidum in the conditions of the Eastern Forest-Steppe of Ukraine.
 Methods. The following methods were used in the research: field – study of biological, ecological features of growth and development of productivity and quality of the crop; mathematical and statistical – used to process experimental data.
 Results. On average, over the years of research, the highest field germination of Sorghum vulgare and Sorghum orysoidum seeds was observed at the optimal sowing dates, i.e. early to middle May: and in ‘Dniprovskyi 39’ variety of Sorghum vulgare it was 88.1 and 87.3%, while in Sorghum orysoidum variety ‘Samaran 6’ 87.6 and 87.1%. In the early sowing dares, the field germination of seeds was lower on average in the experiment by 11.0–12.3%. Tillering of the plants depended on the studied varieties and averaged 1.1–1.2 shoots/plant in ‘Dniprovskyi 39’ and 1.0–1.3 shoots/plant in ‘Samaran 6’. The height of plants in the experiment was 118.2–122.3 cm in ‘Dniprovskyi 39’ and 112.8–116.2 cm in ‘Samaran 6’. The diameter of the stem of sorghum plants on average in the experiment ranged from 1.5 to 1.6 cm. The leaf area during the stages throwing of panicle – flowering reached a maximum for sowing seeds in the early and middle May and amounted to 37.4 and 36.7 thousand m2/ha in ‘Dniprovskyi 39’ and 36.8 and 35.9 thousand m2/ha in ‘Samaran 6’. Optimal sowing of sorghum seeds contributed to the formation of high crop productivity: in ‘Dniprovskyi 39’, grain yield was 7.1 and 6.8 t/ha, biomass yield 37.4 and 35.6 t/ha; in ‘Samaran 6’, grain yield was 6.4 and 6.1 t/ha, biomass yield 35.9 and 33.6 t/ha.
 Conclusions. It was found that the field germination of seeds mostly depends on weather conditions in the research years (32.1%) and sowing dates 23.4%. Varietal characteristics influenced much less, with the share of influence of 8.4%. Early sowing dates (late April), in comparison with the optimal terms (early to middle May) reduced the grain yield of ‘Dniprovskyi 39’ by 4.2–12.6% and ‘Samaran 6’ by 4.7–9.4%; biomass yield by 4.8–9.6% and 6.4–10.6%, respectively. Biometric indicators of plant growth and development were also higher. As a result of correlation-regression analysis, a close relationship was found between grain yield and leaf area. The correlation coefficient was R = 0.9454 ± 0.163 and 0.997 ± 0.037, and the coefficient of determination was R² = 0.8939 and 0.9946. According to Student criteria, tf = 5.81 > t0.05 = 2.78 and tf = 27.14 > t0.05 = 2.78. A strong correlation was observed between grain yield and plant height with a coefficient of determination R2 = 0.842 and a correlation coefficient R = 0.918 ± 0.199 and between biomass yield and plant height, respectively R2 = 0.7065 and R = 0.841 ± 0.271. According to Student criteria, tf = 3.10 > t0.05 = 2.78 and tf = 4.62 > t0.05 = 2.78.