Submitted to: Arkansas Experiment Station Research Series
Publication Type: Experiment Station
Publication Acceptance Date: August 1, 2001
Publication Date: N/A
Interpretive Summary: Interpretive summary not required.
Technical Abstract: A naturally-occurring, stable isotope of carbon (**13C) is fixed at different rates in rice and barnyardgrass (BYG) during the photosynthetic process because of a different physiological and biochemical makeup of the two species. We used this key difference between the two species to develop a prediction equation that enabled us to determine the relative distribution and amounts of roots produced by weed-suppressive (PI 312777) and non-suppressive (Lemont) rice cultivars when competing against barnyardgrass in field soils. An important advantage of this method is that it accurately determines the content of BYG and rice roots present in mixtures without requiring that the roots of the two species be manually separated. PI 312777 roots were more competitive than those of Lemont, both within and between the rice rows, and BYG roots were most prevalent between the rows. These results suggest that root-root competition may play a significant role in the natural suppression of BYG by PI 312777 under field conditions.