Seed yield and quality of switchgrass formed in different plant tiers

Purpose. To establish the features of yield formation and seed quality in switchgrass (Panicum virgatum L.) depending on its location on the plant – panicles of the 1st and 2nd tiers. Methods. Laboratory, measuring and weighing, mathematical and statistical. Results. There was no significant difference in the yield of cleaned seeds depending on the place of their formation. On average over four years, the yield of seeds from panicles of the first tier was 91.9% and from the second tier 90.6%. It was found out that in the Central Forest Steppe of Ukraine, the yield of switchgrass seeds significantly depended on both the growing conditions (year) and the panicle tier. On average over the years of research, significantly higher seed yield was formed on the panicle of the first tier of both varieties. It was 0.83 g on the panicle of the first tier in variety 'Cave-in-Rock' and 0.70 g in 'Sunburst'. On the panicle of the second tier, the productivity was significantly lower − by 0.35 and 0.31 g, respectively (LSD0.05 tier = 0.24), and was 0.48 g and 0.39 g per panicle. Any significant difference based on varietal characteristics was not detected. The biggest influence on seed yield made cultivation conditions of the year (47.7%) followed by panicle layer (32.9%). The influence of other factors and their interaction was insignificant. The quality of the seed depended both on varietal characteristics and on the place of its formation on the plants. On average, over four years, the seed quality indicators - germination energy and germination – from panicles of the first tier were significantly higher in ‘Cave-in-Rock’, amounting 33% and 34%, respectively. In the second tier, on the contrary, the indicators were higher in ‘Sunburst’ and amounted to 35% (LSD0.05 variety = 0.3%). Conclusions. The yield and quality of switchgrass seeds was significantly affected by cultivation conditions of the year, varietal characteristics and the place of grain formation. The highest yield was formed on the panicle of the first tier in both varieties. 'Cave-in-Rock' formed significantly higher seed yield on the panicles of all tiers, compared to 'Sunburst'. A significantly higher seed germination and germination energy was obtained with the seeds harvested from the panicles of the first tier.