INHIBITION OF SEED GERMINATION AND EARLY DEVELOPMENT BY LEAF LITTER EXTRACTS

Authors: Halvorson, Jonathan; Belesky, David; Godwin, Harry

Submitted to: Ecological Society of America Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/12/2003
Publication Date: 8/1/2003
Citation: Halvorson, J.J., Belesky, D.P., Godwin, H.W. 2003. Inhibition of seed germination and early development by leaf litter extracts. PP 136-137 IN Abstracts of the Meetings of the Ecological Society of America, August 3-8, 2003, Savannah, Georgia.

Interpretive Summary:

Technical Abstract: Silvopastoral management strategies in hill-land Appalachia seek to expand spatial and temporal boundaries of forage production and promote ecosystem integrity through a combination of tree thinning and understory pastures. Little is known about forage establishment in the understory, which may be impacted by competition with trees for light or water, or by the physical and chemical effects of deciduous tree litter. To gain understanding of forage establishment, we determined the effects of water extracts of leaf-litter from common Appalachian tree species; yellow poplar, Liriodendron tulipifera, red maple, Acer rubrum, white oak, Quercus alba, and eastern white pine, Pinus strobus, on germination and seedling growth of forage species. Leaf extracts added to soil inhibited seedling root elongation of white clover, Trifolium repens (cv Huia), with greatest inhibition caused by Liriodendron and Acer, species with highest rates of decomposition. Conversely, extracts from tree species with relatively slow decomposition rates, Pinus and Quercus, had little impact on seedling root elongation. The effects of Liriodendron leaf extract persisted and decreased dry mass of white clover after a 4-week growth period relative to other extracts. Seedling growth might be diminished by immobilization of soil nutrients by microorganisms, stimulated by the litter extract, or by allelopathy. Liriodendron litter extract delayed seed germination for several forage species, especially legumes, but germination resumed immediately after washing the extract from the seeds. Water soluble compounds that inhibit seed germination and impair seedling growth may improve overall seedling success by preventing premature growth early in the season but could compromise forage establishment as an understory crop. Management practices that account for litter impacts are needed to ensure successful sward establishment.