Allelopathic effects of Quercus spp. on crops of Garhwal Himalaya

The allelopathic influence of Quercus glauca Thunb, and Q. leucotrichophora A. Camus was tested on three crops viz; wheat (Triticum aestivum), mustard (Brassica campestris) and lentil (Lens culinaris). In bioassay studies, aq ueous extracts of dried fresh leaves, leaf liner and flaked off bark suppre ssed the germination, plumule and radicle length of all test crops. In pot culture, soil amended with leaf litter and bark also suppressed the germina tion, shoot length and dry mater: of test crops. The rhizosphere soil of bo th tree spp. also significantly suppressed the pigment contents and dry mat ter of all test crops.