IMPACTS OF WEEDS AND PHYSIOLOGICAL STRESSES IN RICE
Location: Dale Bumpers National Rice Research Center
Title: FLOWERING OF RED RICE ACCESSIONS FROM ARKANSAS AND CLEARFIELD CULTIVARS IN THE GRAND PRAIRIE
Submitted to: Arkansas Agricultural Experiment Station Research Series
Publication Type: Experiment Station
Publication Acceptance Date: June 27, 2006
Publication Date: August 8, 2006
Citation: Shivrain, V.K., Burgos, N.R., Gealy, D.R., Black, H.L., Estorninos, L.E. 2006. Flowering of red rice accessions from Arkansas and Clearfield cultivars in the Grand Prairie. In: Norman, R.J., Meullenet, J.-F., Moldenhauer, K.A.K., editors. B.R. Wells Rice Research Studies 2005, Arkansas Agricultural Experiment Station Research Series 540. p. 230-239.
Differences in Clearfield (CL) cultivars, planting time, and flowering time of red rice (RR) may have significant impact on the transfer of imazethapyr-resistant gene to red rice. Objectives in this study were to 1) evaluate the flowering behavior of RR accessions and CL rice cultivars with respect to planting dates, 2) determine yield losses in CL cultivars as affected by the presence of different accessions of RR, and 3) determine outcrossing rates between CL cultivars and RR accessions. The experiments were conducted at the Rice Research and Extension Center (RREC), Stuttgart, Ark., in the summer of 2005. The experimental design was split-split plot with three replications.
Planting time (4), CL cultivar (2), and RR accessions (12) were main-, sub-, and sub-sub plot, respectively. Each RR accession was planted in the middle of 9-row, 12-ft long plots with four rows of CL rice on both sides. Data on emergence, flowering, agronomic traits, and yield were recorded. At maturity, RR plants were bagged and harvested to collect seeds for outcrossing rate determination. Strawhull RR in general emerged faster than brownhull and blackhull RR. Red rice emergence varied from 10 to 35 days after planting (DAP) among and between accessions across planting dates. Earlier planted CL rice and RR accessions took longer to flower than later planted ones. Flowering period of RR accessions ranged from 88 to 128, 87 to 117, 79 to 118, and 71 to 116 DAP, in the first, second, third, and fourth planting, respectively. In all plantings, there was synchronization in flowering (50%) between both CL cultivars and at least six RR accessions. Yield losses in CL161 from red rice competition were higher than those of CL XL8. Red rice produced 50% less tillers in CL XL8 than in CL161 plots. Outcrossing rates will be determined in the summer of 2006.