Allelopatic Effects of Capparis spinosa, Herttia angustifolia and Peganum harmala on Germination and Seedling Growth of Wheat and Alfalfa

An experiment was conducted to investigate the allelopathic effect of three range species، C. spinosa، P. harmala and H. angustifolia on germination and seedling growth of alfalfa and wheat. The experiment was performed at the Faculty of Natural Resources، Yazd University، in 2002. A completely randomized design with three replications was carried out in a factorial combination of three plant extracts (C. spinosa، P. harmala and H. angustifolia) and distilled water as control، two extract concentrations (50% and 100%) and two target species (alfalfa and wheat). Results indicated that the C. spinosa extract caused the greatest inhibitory effect on test plants. Reductions in seed germination، shoot length and weight were 86، 98 and 99%، respectively compared to control. Results of this experiment also showed that C. spinosa extract had a highly significant inhibitory effect on root length and weight when compared to control. Between two concentrations، 100% concentration has more inhibitory effect on the average of germination and shoot weight as well as shoot length. But، there was no significant difference between root weight and root length. The results of this experiment also showed that the inhibitory effects of both concentrations were higher on alfalfa than wheat.