Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2005
Publication Date: 5/1/2005
Citation: Gealy, D.R., Estorninos, L.E., Gbur, E.E., Chavez, R.S. 2005. Interference interactions of two rice cultivars and their F3 cross with barnyardgrass (Echinochloa crus-galli) in a replacement series study. Weed Science. 53:323-330. Interpretive Summary: Barnyardgrass is the most troublesome weed in rice of the southern U.S. A pot study was conducted to determine the competitive effectiveness of a weed-suppressive rice variety (PI 312777), a non-suppressive variety (Lemont), and a hybrid of the two (PI 312777 x Lemont), against barnyardgrass. in the southern U.S. PI 312777 reduced stem weight, stem number, and root weight of barnyardgrass to the greatest extent, Lemont suppressed growth the least, and the effects of the hybrid were intermediate. Thus, increased biomass of stems and roots, and increased numbers of stems may be useful traits for breeding programs aimed at increasing the natural weed suppression potential of rice in the U.S. Because the hybrid variety was much less suppressive than its naturally suppressive parent, significant improvements will be necessary before this variety can be commercialized.
Technical Abstract: Barnyardgrass has been the most frequently reported troublesome weed in rice because it is an aggressive invader, is difficult to control, and reduces yields significantly. A replacement series was conducted to determine how a naturally suppressive cultivar (T65*2/TN 1; PI 312777), a non-suppressive cultivar (Lemont), and a cross between the two (PI 312777 x Lemont) would interfere with barnyardgrass in the southern U.S. The rice cultivars did not differentially affect plant heights of barnyardgrass. Graphical illustrations of shoot dry weight, root dry weight, and tiller production for the three rice cultivars indicated that PI 312777 suppressed barnyardgrass growth to a greater extent than did the other two cultivars. Lemont suppressed barnyardgrass minimally, while suppression levels of PI 312777 x Lemont were intermediate between the two parents. Increased shoot biomass and tiller production may be important traits when selecting for weed suppressive rice cultivars in the U.S. Because the PI 312777 x Lemont cross typically was less suppressive than its PI 312777 parent, significant genetic improvements will be necessary before it is suitable for commercial use in a reduced herbicide production system.