Effects of Phenolic Extracts of Canola (Brassica napuse L.) on Germination and Physiological Responses of Soybean (Glycin max L.) Seedlings

   Phenolic extracts of canola (Brassica napuse L.) contains substances that inhibited the germination and seedling growth of soybean (Glycin max L.). These compounds also affect activity of some enzymes. Hear, we investigated the allelopathic effects of various canola plant parts on soybean germination, seedling growth, and biochemical aspects. Phenolic extract of canola shoot (including leaf, stem, and flower) and root were made by methanol 70%, to determine their effects on germination, seedling growth, and fresh and dry weight of hypocotyl and radicle of 8-d old soybean seedlings, and their effects on activity of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), polyphenoloxidase (PPO), protein content of hypocotyl and radicle, and lipid peroxidation (MDA) of radicle. The results showed that there were no significant differences in CAT activity and protein content. Increasing the phenolic extract concentration of separated canola plant parts decreased soybean germination and seedling length and weight, radicle was more sensitive to extract source than hypocotyl. The POD and SOD activity of radicle and hypocotyl and lipid peroxidation of radicle were increased by concentration of both phenolic extracts compared with control. The PPO activity of radicle and hypocotyl was increased under root extracts, but shoot extracts had not significantly effects. The degree of toxicity of canola root part was more than shoot part.