Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/2004
Publication Date: 6/20/2004
Citation: Gealy, D.R., Estorninos, L.E. 2004. Hybridization between red rice and rice in the U.S.: Implications for gene flow and ferality. 4th International Weed Science Congress. Abstract p. 76. Interpretive Summary:
Technical Abstract: Imidazolinone-resistant rice cultivars have been increasingly adopted in the southern U.S. since their initial introduction in 2002, largely due to the improved control of red rice in these systems. Although promising, herbicide-resistance technology has raised concerns about potential hybridization and gene flow between rice (Oryza sativa L.) and its weedy relative, red rice (Oryza sativa L.), and the potential development of herbicide-resistant or feral red rice populations. SSR marker analysis and phenotypic analysis of segregating populations are being employed in Arkansas to quantify, identify, and track red rice hybrids in grower and research fields. Outcrossing rates between red rice and herbicide-resistant or non-resistant rice have been variable, but nearly always less than 0.5%. Outcrossing depends on a number of factors, including red rice ecotype, rice cultivar, vertical and/or horizontal distances between panicles, synchronization of flowering periods, and seed production, as well as environment. Subsequent introgression of hybrid traits into the red rice population can be mitigated by additional factors including delayed flowering periods and/or low seed set in hybrids. Although gene flow between rice and red rice in U.S. rice fields is likely to remain a significant issue, establishment of feral populations of hybrid, weedy rice in non-rice or non-agricultural areas appears to be of relatively low risk due to the minimal availability of desirable O. sativa habitat outside of rice fields. Integrated strategies that address short- and long-term challenges of red rice control and resistance management will be necessary to optimize sustainability of rice production in the U.S.