Abstract
The allelopathic effects of leaf exteracts of Datura sp., Cenicus benidictus, Silybum marianum and
Plantago lanceolata on seed germination of main weeds of Mashhad region investigated. Seed
germination of the weeds and commercial plants showed different reactions. Seed germination of
the weeds decreased while their Mean Daily Germination (MDG) increased. In some cases,
germination rate increased in comparison with control (treated with distilled water). Lowest seed
germination belong to Sylibum marianum (5%) and Chinicus benidictus (10%) on Descoronia