Seed size distribution, germination, and emergence of 6 switchgrass cultivars

Abstract

Switchgrass (Panicum virgatum L.) has potential as a forage and biomass crop, but difficult establishment has limited its use. Germination and emergence were studied for 6 cultivars of switchgrass ('Alamo', 'Blackwell', 'Cave-in-Rock', 'Kanlow', 'Pathfinder', and 'Trailblazer'). Germination studies were conducted to determine the effect of light on germination and coleoptile length, and to determine the effect of seed size (40, 50, 60, 70, and 80 degrees air valve settings for a South Dakota seed blower) on germination. A greenhouse study was also conducted to examine the effect of seed size, planting depth, (5, 10, and 20 mm), and soil type (sand and 2 silt loams) on emergence. Germination of unsized seed increased linearly as duration in the germination chamber increased from 7 to 21 days for all cultivars. Although presence of light did not affect germination, coleoptile length under continuous darkness averaged 4.1 cm and was greater than the 1.0 cm measured for those with daily light exposure of 16 hours. Both germination and emergence increased nonlinearly as seed size increased. For both silt-loam soils, emergence was low and not affected by planting depth. A nonlinear decline in emergence with increased planting depth was detected in sand 7 days after planting, but not after 14 and 21 days. Results of the study indicate that seed size and soil texture had a greater effect on emergence than did planting depth down to a depth of 20 mm.