|MOLDENHAUER, KAREN - University Of Arkansas|
Submitted to: International Allelopathy Congress
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/2014
Publication Date: 8/1/2014
Citation: Gealy, D.R., Moldenhauer, K.A., Duke, S.E. 2014. Root distribution and interactions between allelopathic rice and c4 grass weed species as determined by 13c isotope discrimination analysis . In: Proceedings of the 7th World Congress on Allelopathy. Vigo, Spain. International Allelopathy Society. International Allelopathy Congress. p. 224.
Technical Abstract: Cultivars which carry allelopathic traits (traits that enable them to suppress weeds) could improve the economical management and sustainability of rice production. Interactions between roots of rice and weeds are thought to be modulated by the weed-suppressive activity of some rice cultivars, but these phenomena are difficult to measure and not well understood. A two-year field study evaluated the above-ground crop-weed interactions and root distribution of allelopathic rice cultivars (including PI 312777 and Taichung Native 1), non-supressive rice cultivars, and two C4 grass weed species sprangletop (Leptochloa fusca (L.) Kunth var. fascicularis (Lam.) N. Snow) and barnyardgrass (Echinochloa crus-galli (L.) Beauv.). The allelopathic cultivars and other weed-suppressive cultivars produced more tillers and suppressed both weed species to a greater extent than other cultivars. 13C isotope discrimination analysis of intermixed root samples showed that the allelopathic cultivars produced a greater fraction of their total root mass in the upper 5 cm of soil compared to the non-suppressive cultivars. These trends in root distribution were observed early in the season (pre-flood) as well as at crop maturity in both weed-free and weed-infested plots. Barnyardgrass reduced rice yield and root mass more than did sprangletop. Our results demonstrated that roots of the allelopathic cultivars used in these studies grew aggressively and proliferated near the soil surface. Rice plant types exhibiting such optimized root distribution and allelochemical exudation traits in combination with high tillering and yield might be useful for improved weed management and crop production in organic rice or other reduced-input systems.