Allelopathic effects of Pakistani weeds: Euphorbia granulata Forssk.

The aqueous extract of Euphorbia granulata Forssk., prepared in Hoagland's nutrient solution; and underlying soil significantly inhibited germination and radicle growth of Dichanthium annulatum, Cynodon dactylon, Setaria italica, Pennisetum americanum, Euphorbia pilulifera, Oxalis corniculata and Lactuca sativa invariably in laboratory bioassays. Artificially decomposed E. granulata litter in a nutrient medium significantly reduced germination and fresh and dry weight of the aforementioned test species. The toxins affected germination and growth independently. The local dominance of this weed over its counterparts was primarily due to allelopathy, and it is therefore suggested that its litter must be removed from the fields during weeding.