Research was conducted to evaluate the weed suppression potential of ‘Rondo’ (4484-1693; PI 657830), a sister line (4484-1665), and other indica rice lines against barnyardgrass in field plots in Stuttgart, AR, using minimal herbicide inputs in two separate 3-yr experiments. Under weed pressure, Rondo and the sister line (4484-1665) generally produced yields that were comparable to those of weed-suppressive indica standards and approximately 50% greater than those of the least-suppressive commercial cultivars, such as ‘Kaybonnet’, ‘Katy’, and ‘Lemont’. Rice yield under weed pressure was correlated with weed-free yield and harvest height. Indica lines tended to produce more tillers than did the commercial cultivars. Tillering potential under weed-free conditions was not correlated with weed suppression or yield loss; however, tillering under weed pressure was strongly correlated with weed suppression and biomass, and yield and yield loss under the weed densities in these experiments. Rondo is presently being used for commercial organic rice production in Texas, in part due to its high yield potential and ability to suppress or tolerate rice pests, including weeds. Our results suggest that the weed-suppressive ability of Rondo and the other indica lines evaluated in these experiments is superior to that of many commercial cultivars.

Nomenclature: Barnyardgrass, Echinochloa crus-galli (L.) Beauv.; rice, Oryza sativa L.