Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)

First Advisor

Co-Eric P. Webster

Second Advisor

James L. Griffin


Studies were conducted to evaluate crop tolerance and yield of glufosinate-resistant rice lines treated with glufosinate throughout the season. In addition, studies were conducted on harvested seed treated with glufosinate at various growth stages to evaluate seed weights, germination, and seedling vigor. Weed control with glufosinate alone and in combination with other herbicides was evaluated. Red rice control with different glufosinate rates and timings under 5, 10, and 20 cm permanent flood depths was also evaluated. In the tolerance study, CPRS PB-13 injury was less than 10% for all timings and no differences in yield were detected when compared with the nontreated; BNGL HC-11/62 injury was less than 15% for all timings and yield was reduced at the 3- to 5-lf, pre-boot, and boot timings compared with the nontreated. Glufosinate applications throughout the season did not affect CPRS PB-13 seed weights, germination, and seedling vigor when expressed as a percent of nontreated. No differences occurred for BNGL HC-11/62 seed weights and seedling vigor expressed as a percent of nontreated; however, germination was reduced 14 d after initiation at 22 C with a pre-boot glufosinate application. Tank-mixing 0.42 kg/ha glufosinate with other herbicides resulted in antagonism when compared with an increased rate of glufosinate at 0.84 kg/ha with the same combinations. At 14 d after treatment, 0.42 kg/ha glufosinate controlled barnyardgrass and broadleaf signalgrass 85 and 86%, respectively. The addition of propanil and triclopyr enhanced annual sedge control over a single application of glufosinate. At 14 DAT, a synergistic response for spreading dayflower occurred for all tank-mix combinations with the exception of halosulfuron and triclopyr; however, at 28 DAT, spreading dayflower control was less than 80% with all treatments. Red rice control was 87 to 98% and responded differently to flood depth, glufosinate timings, and years. Red rice control at both 2 and 3 weeks after treatment was reduced at the 20 cm flood depth for the 2- to 3-lf application timing compared with the 5 and 10 cm flood depths. Late season application had varied results for red rice control and permanent flood depth.