Allelopathic potential of leaf, stem and root extracts of some Iranian rice (Oryza sativa L.) cultivars on barnyardgrass (Echinochloa crus-galli) growth

Selection of rice cultivars with greater allelopathic potential can be used as a tool in sustainable weed management. Two laboratory and greenhouse experiments were conducted to identify the potential allelopathic effects of leaf, stem and root extracts of ten Iranian rice (Oryza sativa L.) cultivars (Mosa Tarom, Hasani, Champa, Anbarbo, Fajr, Neda, Khazar, Mehr, Salari and Kamfiruzi) on barnyardgrass (Echinochlea crus-galli) growth. Results showed that allelopathic potential of leaf extract was more effective than root and stem extracts of rice cultivars. Among the rice cultivars, Kamfiruzi and Salari allelopathic effects caused a significant decrease (p≤0.01) in seed germination (46 and 45%), radical length (93 and 92%), shoot length (65 and 57%) and fresh weight (68 and 68%) of barnyardgrass in laboratory assay as well as weed biomass (67 and 62%) and height (57 and 56%) in greenhouse experiment. There were significant direct effect, path coefficient, between weed radical length, radical fresh weight (p=0.29, p</=0.05) and shoot fresh weight (p=0.45, p</=0.01). In general, the leaf and root extracts of Kamfiruzi and Salari which were native cultivars showed a prominent allelopathic effect on the growth of barnyardgrass. Our results suggest that there is a possibility of developing a new ecological weed management strategy using rice cultivars with higher allelopathic potential. This means breeding of rice cultivars for higher allelopathic potential might provide natural herbicides for growers.