Effect of the elements of cultivation technology on the productivity and ethanol yield from sugar sorghum in the Central Forest-Steppe of Ukraine

Abstract

Purpose. To establish the effect of elements of cultivation technology on the productivity and ethanol yield from sugar sorghum. Methods. The biological, calculation and statistical methods were used in the research. Biological methods included conducting field experiment. The bioethanol yield was determined by the calculation method. The obtained results were processed by statistical methods: descriptive statistics and analysis of variance ANOVA. Results. The degree of effect of varietal characteristics, fertilizers, sowing date and weather conditions on the productivity and bioethanol yield from sugar sorghum was established. Fertilizer dose increase by 1 kg a.i. (NPK) in the range from 0 to 80 kg/ha allowed to increase the bioethanol yield by an average of 14.1 kg/ha, but the fertilizer efficiency in the NPK fertilizer dosage range from 80 to 160 kg/ha was only 2,2 kg/ha of bioethanol per 1 kg a.d. (NPK) fertilizer. The bioethanol yield from the ‘Medovyi’ hybrid averaged 2.82 t/ha, which is 17.7 % more than from the ‘Sylosne 42’ variety (2.32 t/ha). The highest bioethanol yield (2.66–2.74 t/ha) was achieved by sowing seeds in the early and middle of May. Conclusions. The bioethanol yield from sugar sorghum was the most affected by weather conditions (39.0 %) and fertilizers (28.5 %), the degree of influence of varietal characteristics and sowing date were 5.2 and 2.7 %, respectively. Under the conditions of severe drought (hydrothermal index (by Selianinov) 0.45), the yield of green biomass of sugar sorghum decreases by 30–32 %, the sugar content of juice by 32–33 %, and the bioethanol yield 2 times in comparison with sufficiently humid weather conditions. (hydrothermal index of 1.45). Fertilizer application N80P80K80 allowed to increase the yield of green biomass of sugar sorghum by 24.9 t/ha, the sugar content of juice by 1.5 % and the bioethanol yield by 1.13 t/ha. Increasing the fertilizer dose by half from N80P80K80 to N160P160K160 contributed to a slight increase in the productivity and bioethanol yield. In 'Medovyi', the yield of green biomass increased by 6.6 t/ha, the sugar content of the juice by 1.3%, the bioethanol yield by 0.5 t/ha compared with ‘Sylosne 42’. Early sowing of sugar sorghum (late April) reduces the yield of green biomass by 6.6 t/ha, juice sugars by 0.5 %, bioethanol yield by 0.34 t/ha compared to optimal terms (early and middle May).