Purpose. To find out the dependence of sugar sorghum productivity on varietal characteristics, the sowing date and the harvesting date in the zone of insufficient moisture in the Eastern Forest-Steppe of Ukraine.Methods. The biological and statistical methods were used in the research. Biological methods included field experiments and monitoring of productivity indicators. The results were processed using the following statistical methods: descriptive statistics, ANOVA, and correlation analysis.Results. The degree of the effect of varietal characteristics, sowing date, harvesting date and weather conditions on the productivity and quality of sugar sorghum biomass have been established. The yield of green biomass, the sugar content of the juice and the dry matter content of sugar sorghum hybrid ‘Mamont’ exceeded the corresponding indicators of the variety ‘Sylosne 42’. Harvesting sugar sorghum of the ‘Sylosne 42’ variety and the ‘Mamont’ hybrid in the wax ripeness phase increased the yield of green biomass by 10.4 and 9.5 %, respectively, the sugar content of the juice by 1.8 times, and the dry matter content by 32.6 and 18.3 %, the crude ash content in this case decreased by 4.6 and 3.0 % compared with the phase of booting.Conclusions. The yield of green biomass depends on the varietal characteristics of sugar sorghum (36.5 %), the sowing date (12.1 %) and the harvesting date (12.2 %). A close relationship (R2=0.76) between the yield of green biomass and the length of the vegetation period of sugar sorghum had been established. To obtain a high yield of green biomass of sugar sorghum, its seeds should be sown in late April – early May, and the biomass should be collected no earlier than September in the phase of full ripeness of seeds. The dominant effect on the variation in the sugar content of the juice made the harvesting date (68.1 %). The effect of sowing dates, weather conditions and varietal characteristics on the sugar content in the juice was significantly less and amounted to 2.7, respectively; 2.3 and 1.0 %. Harvesting sugar sorghum in the wax ripeness phase provided a 1.8 times higher sugar content of the juice compared to the phase of booting, and further transfer of harvesting time to the full ripeness phase insignificantly increased the sugar content of the juice. The accumulation of dry matter in sugar sorghum plants was influenced by the harvesting date (54.5 %), the sowing date (5.2 %), weather conditions (3.3 %) and varietal characteristics (0.3 %). Delay in sowing date for every 10 days since the end of April leads to a decrease in the dry matter content in the biomass of sugar sorghum by an average of 1%. Extension of the vegetation by 1 day due to the later harvesting of biomass increases the dry matter content by 0,25 %. The influence of varietal characteristics (12.4 %), sowing date (1.9 %) and harvesting date (23.6 %) on the content of crude ash in the sugar sorghum was established. With an increase in the growing season, the content of ash elements in the biomass of sugar sorghum, both varieties and hybrids, decreased significantly. In terms of yield of green biomass (91.5 t/ha), sugar content of juice (12.7 %) and dry matter content (24.6 %), Sorghum sugar hybrid 'Mamont' exceeded the 'Sylosne 42' variety, the corresponding indices of which were 70,8 t/ha, 12 % and 24.0 %, while the content of ash elements in the biomass of the hybrid was lower than that of the variety.
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