Comparison of Allelopathic Potential of Rice Leaves, Straw, and Hull Extracts on Barnyardgrass

The use of rice (Oryza sativa L.) allelopathy for weed control is a new technology in agronomy. A laboratory bioassay using water extracts was conducted to determine the allelopathic potential of rice body parts on seed germination and growth of barnyardgrass (Echinochloa crus‐galli P. Beauv. var. oryzicola Ohwi) and to determine rapid and simple methods for selecting allelopathic rice varieties using genetic characters and phenotypes. In this study, the highest inhibition rate was for ‘Danganeuibangju’ (76.9%) in straw extracts, ‘Dongobyeo’ (74.1%) in the leaves, and ‘Baek’ (31.7%) in the hull. ‘CUBA 65‐v‐58’ (38.6%) had the highest inhibition as a whole (average of leaves, straw, and hull), and there was a higher average inhibitory effect for straw extracts (21.6%) than for hulls (8.2%) and leaves (12.4%). With regard to classification by phenotypic and genetic characteristics, these groups showed a higher inhibitory effect in domestic varieties (14.2%), middle‐maturing varieties (15.3%), varieties of hull color (15.1%), and varieties of awn color (16.0%). These results suggest that rice body parts may be a source of natural herbicides and that it is necessary to develop acceptable selection standards. There may also be genetic variation in rice varieties for their allelopathic potential on barnyardgrass. In the future, it might be possible to develop rice varieties with high allelopathic potential.