Allopathic effect of different organs of Ssunflower on germination of large and small wheat's seed

In order to investigate the effect of seed size on alleviation of allopathic effect of different part of sunflower, an experiment was conducted as a factorial combination with completely randomized design with 4 replications at Islamic Azad university in 2010. Treatments were: wheat seed size(large and small) aqueous extracts of sunflower (leaf, stem and root) and concentrations(0, 15, 20, and 25% (m/v)). The result showed that root aqueous extracts had more negative effect on germination characteristic of large and small seed than leaf, stem aqueous extracts. The highest concentration of sunflower extract had the greatest inhibitory effect on the germination of wheat seeds(43%) and small seed was more sensitive than large seed. For all germination characteristics, large seeds were better than small seeds. Overall, the results showed that the use of large seed reduces the negative effects of sunflower residual on germination.