Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: January 27, 2003
Publication Date: January 27, 2003
Citation: Gealy, D.R., Black, H.L., Yan, W., Rutger, J.N. 2003. WEED SUPPRESSION POTENTIAL IN INDICA RICE LINES FOR THE SOUTHERN U.S. Proceedings of Southern Weed Science Society. 56:303. Technical Abstract: Weed control is one of the key challenges to sustainable rice production systems in the southern U.S. Rice cultivars that naturally suppress weeds have been the topic of numerous recent research efforts worldwide. Several indica rice lines from the Philippines, including `PI 312777', have consistently been suppressive to barnyardgrass in drill-seeded rice in Arkansas and show promise as economically viable components of reduced herbicide systems. Other indica rice cultivars recently imported from China have yielded substantially more than the highest-yielding U.S. tropical japonica commercial cultivars. In a two-year field study at Stuttgart, AR, we compared the barnyardgrass-suppression and yielding abilities of eleven indica cultivars and improved indica lines, and the commercial hybrid rice `XL8' with the southern U.S. commercial tropical japonica cultivars, `Drew' and `Bengal'. In 2001 when no grass herbicide was applied, heavy barnyardgrass infestations resulted in poor weed suppression and low yields for all rice entries. In 2002, the reduced rate of 1 kg/ha propanil was applied at the three-leaf stage to supplement barnyardgrass suppression. XL8 provided 72% visual control of barnyardgrass, while `PI 312777' and the indica x indica crosses, `8004' and `8010' provided 55 to 60% control. By comparison, `Drew' and `Bengal' provided 48 and 40% control, respectively. Visual control levels were usually negatively correlated with mid-season barnyardgrass biomass levels. Although numerous indica cultivars have yielded more than U.S. commercial cultivars in previous studies at Stuttgart, only `4593' from China out-yielded `Drew' and none out-yielded `Bengal' in our studies. Heavy rainfall between rice planting and emergence probably reduced the overall suppression of barnyardgrass in both years. Many of the indica lines lodged before harvest in both years (especially 2001). This led to difficulties in harvest operations and loss of seed, and may account for the relatively few yield differences among cultivars.