Seedling Growth of Three Switchgrass Strains

Seedlings of Pathfinder, Nebr. 28, and experimental ey switchgrass (Panicum virgatum L.) strains were grown in a growth chamber and harvested 1, 2, 3, 4, 6, 8, and 10 weeks following emergence for detection of seedling growth differences among strains. Leaf areas and dry weights of leaf blade and stem axis (stem and leaf sheath) generally increased significantly with each harvest from 4 to 10 weeks. Stem axis and leaf blade dry weights were significantly greater with Pathfinder and ey, respectively, than with Nebr. 28. Final leaf area was significantly greater with ey than with the other strains. Thus, Nebr. 28 (early-maturing) would be less competitive with weeds during establishment than Pathfinder or ey (both are late-maturing). Relative growth rate (RGR), net assimilation rate (NAR), and leaf area ratio (LAR) were similar for all strains, although at the first harvest Nebr. 28 had a lower LAR than the other two strains. RGR, NAR, and LAR generally declined with each successive harvest. The strains appeared to have the same capacity to produce above ground biomass but photosynthate partitioning differed as indicated by leaf and stem comparisons