اثرات دگرآزاري ارقام برنج بر علفهاي هرز سوروف و اويار سلام بذري

Use of crops of allelopathic potential for weed control is one of the important goals of integrated weed management and can reduce pesticide usage, protect environment, reduce crop production costs, and provide a sustainable agriculture system. Newly germinated seeds of ten Northern Iranian rice varieties were allowed to grow for a week and then mix-cultured with barnyardgrass (Echinochloa et-us-go/1i L.) P. Beauv. and umbrella sedge (Cyperus difformis L.) seedlings in pots containing sterilized paddy soil. The tested rice varieties included native Tarom-atri, Binam, Bejar, Dasht, Unda, Haraz, Neamat, and lines 424 and 7165. The potted plants were allowed to grow under field conditions, weeds were harvested 10 days after being transplanted, and compared with controls. The results indicatied a growth reduction of mix-cultured weeds with most of the rice varieties. The barnyardgrass fresh weight reduction ranged from 42 to 72% compared with both control and branyardgrass mixed cultured with non-allelopathic rice (parallel control). The seedling lenght reduction of barnyardgrass ranged from 31 to 55% and 23% compared with control and non allelopathic control, respectively. The umbrella sedge fresh weight reduction ranged from 30 to 52% compared with control and 47 to 63% compared with umbrella sedge mix-cultured non-allelopathic rice control and its seedling length reduction ranged from 31 to 55% and 25-52% compared with control and non-allelopathic control, respectively. In general, Tarom-atri, Neamat and Dasht cultivars are recognized as the cultivars which have the highest allelopathic activity.