Productivity of switchgrass (Panicum virgatum L.) varieties of different terms of ripening

Purpose. To determine the formation of productivity (yield of vegetative mass, content of cellulose and hemicellulose, zinc and iron) of different varieties of switchgrass. Methods. Research on the agrotechnology of switchgrass was conducted at the Yaltushkiv Experimental Breeding Station. The predecessor of switchgrass was winter wheat. The experiments were set up in accordance with generally accepted methods. Yield was determined in sections, cellulose content, hemicellulose content – zinc and iron content – by atomic absorption spectrometry. Results. It was found that the yield of switchgrass biomass varied significantly over the studied varieties. Thus, the highest yield was obtained by growing varieties ‘Shelter’ (mid-ripening), ‘Cave-in-Rock’ (mid-ripening), ‘Morozko’ (mid-ripening), ‘Carthage’ (late-ripening) and ‘Kanlow’ (very late-ripening) and ranged between 19.3 and 21.6 t/ha at actual humidity or 11.1–16.7 t/ha of dry mass. However, the highest yield of dry mass was provided by growing varieties ‘Morozko’ and ‘Kanlow’, 16.7–17.9 t/ha. Yield of early-ripening switchgrass varieties was at the level of 12.9–16.7 t/ha at actual humidity or 8.9–11.5 t/ha of dry weight. It should be noted that of the seven mid- and late-ripening varieties, five had dry weight yield at the level of two early-ripening varieties (‘Forestburg’ and ‘Nebraska’). Thus, the highest yield of biomass is provided by growing mid- and late-ripening varieties of switchgrass. The highest content of cellulose was in late-ripening varieties of switchgrass. No significant difference was found between early and late-ripening varieties. It should be noted that the content of hemicellulose almost did not change over the studied varieties and ranged between 14.1 and14.7%. In the dry biomass of switchgrass, the cellulose content was 1.4–1.5 times higher in comparison with the biomass of actual moisture (64.2–68.0). The hemicellulose content was 20.4–21.3%, depending on the variety of switchgrass. It should be noted that their content did not change significantly over the studied switchgrass varieties, both at actual humidity and in terms of dry weight. The iron content was 2.6–2.7 times higher than zinc 1.23–1.27 mg/100 g. Conclusions. The yield of biomass of switchgrass varies from 12.9 to 21.6 t/ha at actual humidity that equals 8.9 to 16.7 t/ha of dry mass. The highest yield of dry mass is provided by the cultivation of switchgrass varieties ‘Morozko’ and ‘Kanlow’ (16.7–17.9 t/ha). The biomass contains 45.2–46.9% of cellulose, 14.2–14.5% of hemicellulose, 0.46–0.47 mg/100 g of zinc and 1.26 mg/100 g of iron. It is recommended to use them in breeding programs to create high-yielding varieties of switchgrass.