Allelopathic effects of root exudates from wheat, oat and soybean on seed germination and growth of cucumber

We examined the allelopathic effects of root exudates from wheat, oat and soybean on germination and growth of cucumber seedlings. We used a special device to collect the root exudates and studied their allelopathic effects. wheat, oat and soybean root exudates had different allelopathic effects on seed germination of cucumber. Wheat root exudates at higher concentrations promoted the seed germination, but low concentrations were inhibitory. A similar pattern was observed with exudates from soybean, but the opposite trend was observed with oat roots exudates. These three types of root exudates also had variable effects on the seedling growth of cucumber. The integrated allelopathy index (RI) showed that most root exudates promoted the seedling growth than other treatments and control. The wheat root exudates of 50% concentration were most stimulatory to growth (RI = 3.333), followed by 100% concentration (RI = 2.488). The higher concentrations of wheat root exudates stimulated the seed germination and seedling growth of cucumber. Contrarily, oat root exudates at 100% concentration inhibited the seedling growth of cucumber.