Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract only
Publication Acceptance Date: 2/1/2001
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: A study was conducted at Stuttgart, Arkansas in 1999 to (1) compare nitrogen uptake between red rice and rice and (2) to determine the proportion of soil-applied nitrogen taken up by red rice. Stuttgart strawhull red rice and Drew rice were seeded in alternate rows spaced 19 cm apart, at eight rows per plot. Before permanent flood, two metal squared were placed in the middle of each plot. Each square enclosed two rice and two red rice rows. Pelletized **15N urea fertilizer was applied at 0, 50.4, 100.8, 151.2, and 201.6 kg ha**-1 in the square. Regular urea fertilizer was broadcast outside the squares at 100.8 kg N ha**-1. The experiment was a randomized complete block with four replications. Above-ground biomass was harvested from one square of each plot at panicle initiation and two weeks after heading. Tissues were processed for total N and **15N analysis. At two weeks after heading, biomass of red rice (828 g gm**-2) was greater than that of rice (468 g m**-2) at 0 N rate. The difference in biomass production increased with N rates. At 151 kg N ha**-1, red rice produced 2.5 times more biomass than rice. The total N uptake at panicle initiation was similar between red rice and rice at low N rates. N uptake by red rice continued at higher N rates but that of rice leveled off. At two weeks after heading, total N uptake by red rice was greater than rice especially at higher N rates. Two weeks after heading, red rice had more total N in the top leaf, sheath, and panicle than rice. The majority of N was in the top leaf at panicle initiation. The percentage of N in the flag leaf was higher in red rice than in rice. The percentage of N in the sheath was higher in rice than in red rice. Overall, red rice was more efficient in taking up and utilizing nitrogen than rice.