Effect of sunflower (Helianthus annuus) alcoholic extract on germination, vegetative growth, some enzymes activities of Avena ludoviciana

In order to evaluate the allelopatic potential of sunflower alcoholic extract against winter wild oat (Avena ludoviciana) at germiantion and vegetative growth stage two expriments were coducted in Islamic Azad University، Shoushtar branch at 2012. Both expriments were laid out according to Completely Randomized Design with five replications and treatments were various concentration of sunflower extract (0، 5،10،15 and20 gr L-1). Results indicated sunflower alcoholic extract application exhibited gradual rise inhibitory effect on seed germination، seedling weight، antioxidant enzymes activity and -amylase enzyme activity but elevated the mean germination time and malondialdehyde concentration in winter wild oat seedlings. The lowest -amylase enzyme activity was noted at higher levels of extract application (1. 1 nmol seed -1 min-2). Likewise، seedling weight، antioxidant enzyme activities and sucrose synthetesis enzymes activity were declined with sunflower extract application but malondialdehyde concentration increased. Menimum sucrose synthesis activity (1. 36 nmol prot -1 min-2) and highest malondialdehyde concentration (0. 96 nmol grfw-1) was noted at 20 grL-1 concentration of sunflower alcoholic extract application. In conclusion، sunflower alcoholic extract decreased seed germination، seedling growth، -amylase enzyme and sucrose synthetesis enzymes activity of winter wild oat.