Location: Dale Bumpers National Rice Research CenterTitle: Growth characteristics of a weed-suppressive indica x non-suppressive tropical japonica rice mapping population
Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/11/2015
Publication Date: 2/13/2015
Citation: Gealy, D.R., Jia, Y., Pinson, S.R. 2015. Growth characteristics of a weed-suppressive indica x non-suppressive tropical japonica rice mapping population. Weed Science Society of America Meeting Abstracts. 55(263). Available: http://wssaabstracts.com/public/30/proceedings.html
Technical Abstract: The indica rice cultivar, PI 312777, can be highly productive as well as suppressive to C4 grass species such as barnyardgrass (Echinochloa crus-galli). A recombinant inbred line (RIL) mapping population was developed using single seed descent from a cross between ‘Katy’ (non-weed-suppressive) and PI 312777 (weed-suppressive, allelopathic) for the purpose of identifying the genetic basis of weed suppression. Two replications of 15 seeds each of 350 RILs from the mapping population (F7 generation) were drill-seeded in the field in 1.5 m-long, single-row plots spaced 0.6 m apart. Nitrogen fertilizer was broadcast at a rate of 110 kg ha-1 as urea before application of the permanent flood, and plots were maintained weed-free using commercial herbicides. Transgressive variation was observed among several phenotypic traits associated with weed suppression. These included plant height, tiller number, tillering angle (plant type), and days to heading. Five weeks after emergence, the heights of PI 312777 and Katy were 41 and 50 cm, respectively, and the RIL heights ranged from 20 to 69 cm. In a subjective rating of tiller number, where the value for Katy was 1 (few) and the value for PI 312777 was 5 (many), the RILs ranged from 1 to 6. Using the protocol of the International Rice Research Institute to determine tiller angle, where a value of 1 is the most erect and a value of 7 is the most prostrate, the RILs ranged from 1 to 7, and the value for both Katy and PI 312777 was 3. In the late season, maximum plant heights of PI 312777 and Katy were 92 and 108 cm, respectively, and the RIL heights ranged from 60 to 169 cm. Late season tiller angle values for Katy and PI 312777 were 1 and 3, respectively, and the RILs ranged from 1 to 7. Heading for PI 312777 and Katy was 92 and 91 days after emergence, respectively, with RILs ranging from 60 to 139 days. These results will help identify rice genotypes that optimize both weed suppression and crop productivity for reduced-input systems. A subset of these RILs will be selected based on contrasting phenotypes and evaluated in weed-suppression experiments in the field and greenhouse to identify the genetic basis of weed suppression using QTL mapping.