Allopathic Effects of White Top (Cardaria draba) on Germination Characteristics and Growth Seedling of Canola(Brassica napus) and Sweet Corn (Zea mays) Seed

In order to evaluate the allelopathic effects of white top (Cardaria draba (L.) Desv.) water extracts on corn and canola germination characteristics، an experiment was carried out based on CRD design with three replications in agronomy research lab of Yasouj University. Treatments were included of 25%، 50%، 75% and 100% water extract (50 gr dm/L) of root، leaf and stem، inflorescence and whole plant of whitetop and control (distilled water) were applied. Results showed that germination percent and rate، radicle and shoot length and dry weight، and root/shoot length ratio and dry weight were decreased significantly by increasing extract concentration. Effect of shoot extract was greater than of root. Inhibition percent was increased by extract concentration، but there was not significant differences between 75% and 100% extract concentration. Based on the results، canola was more susceptible than maize to allelopathic effect of whitetop extract. Finally based on the results it is possibleto say that whitetop can prevent the germination and growth of canola and sweet corn by producing the allelopathic compounds، and decreasing green surface and undesirable growth of crops.