Phytotoxic Effects of Bunchgrass Residues on Germination and Initial Root Growth of Yellow Sweetclover

Abstract

The subclimax bunchgrasses Arizona fescue and mountain muhly promptly invade disturbances in the climax ponderosa pine forest and develop into dense, persistent, impenetrable communities. Yellow sweetclover and several weed species invade disturbances in the bunchgrass community, flourish briefly, then decline as the bunchgrasses recover the site. Extracts prepared from green foliage and straw of fescue and muhly significantly reduced sweetclover seed germination and retarded speed of elongation and mean radicle length. Leachates from live grass foliage significantly inhibited sweetclover seed germination, suggesting that leaching may be a route of release of the inhibitor.