Seed productivity of switchgrass depending on varietal characteristics

Abstract

Purpose. To establish the features of yield formation and seed quality of switchgrass depending on varietal characteristics. Methods. Laboratory, field, measuring and weighing, mathematical and statistical. Results. It was established that the productivity of switchgrass varietis depends on the ripeness group. A significantly higher seed yield was provided by the mid-late cultivar ‘Cave-in-Rock’, 0.137 t/ha, early-ripening ‘Forestbur’, 0.128 t/ha, and mid-early ‘Nebraska’, 0.124 t/ha, while the yield of other cultivars was significantly lower. The lowest seed yield was provided by the very early variety ‘Dakota’ and late ‘Carthage’ and very late ‘Kanlow’. The highest indicators of seed quality – germination energy and germination – were found in very early ‘Dakota’ variety, 50 and 52%, respectively, and in mid-early ‘Samburst’, 50 and 53%, respectively. Germination energy and seed germination of the early-ripening variety ‘Forestbur’, mid-early ‘Nebraska’, and mid-late ‘Cave-in-Rock’ were 30–34 and 32–35%, respectively, depending on the varietal characteristics, and no significant difference was found. Much lower seed quality was obtained in mid-late varieties, and the lowest – in very late varieties. Analyzing seed quality over the years of research, it was found that its germination depended on the sum of effective temperatures during the growing season. The highest germination of all varieties, 47% was in 2018, which is caused by the sum of effective temperatures over 3539 °С. The 2019 and 2020 growing seasons were less favourable than 2018, but significantly better than 2021. Conclusions. Productivity of switchgrass, seed yield, its germination energy and germination depended on maturity group and growing weather conditions, i.e., the sum of effective temperatures. It was found that the higher the sum of effective temperatures, the higher the seed germination. The highest germination of all varieties, 47%, was obtained for the sum of effective temperatures above 3539 °C. A strong correlation was found between seed germination and the sum of effective temperatures (r = 0.96).