Title page for ETD etd-07022004-211551

Type of Document Dissertation
Author Levy, Jr., Ronald Joseph
Author's Email Address rlevy@agctr.lsu.edu
URN etd-07022004-211551
Title Imidazolinone-Tolerant Rice: Weed Control, Crop Response, and Environmental Impact
Degree Doctor of Philosophy (Ph.D.)
Department Agronomy & Environmental Management
Advisory Committee
Advisor Name Title
James L. Griffin Committee Co-Chair
Steven D. Linscombe Committee Co-Chair
Eric Webster Committee Member
James E. Board Committee Member
James H. Oard Committee Member
Frederick Rainey Dean's Representative
  • Amazon sprangletop
  • reduced tillage
  • red rice
  • imazethapyr
  • Indian jointvetch
Date of Defense 2004-06-25
Availability unrestricted
Field and greenhouse research was conducted from 1999 to 2003 to evaluate weed control in imidazolinone-tolerant (IT) rice (Oryza sativa L.) under various tillage and planting systems, tolerance of IT rice cultivars to imazethapyr rate and application timing, and the impact of IT technology and tillage systems on solids runoff in rice drainage water. In both conventional and reduced tillage systems imazethapyr applied preemergence and postemergence at 70 g ai/ha controlled red rice (Oryza sativa L.), barnyardgrass [Echinochloa crus-galli (L.) Beauv.], Amazon sprangletop [Leptochloa panicoides (Presl) Hitchc.], and rice flatsedge (Cyperus iria L.) 87 to 99%. Indian jointvetch (Aeschynomene indica L.) control with sequential applications of imazethapyr was as high as 70% in water-seeded rice but no more than 54% in drill-seeded rice. With sequential applications of imazethapyr at 70 g/ha, rice yield was 63% greater when water-seeded compared with drill-seeded. Imazethapyr applied to one- to two-leaf or three- to four-leaf rice at 70, 140, and 280 g/ha was more injurious to the IT rice cultivar �CL 161� than to �CL 121�. Shoot:root ratio for CL 161 was not affected by imazethapyr application. For CL 121, shoot:root ratio following imazethapyr application was lower than that observed for CL 161 suggesting that CL 121 shoot fresh weight was inhibited more by imazethapyr than was root fresh weight. Based on shoot fresh weight two weeks after imazethapyr application at 70 g/ha, CL 161 was 1.8 times more tolerant than CL 121 and CL 161 was 2.9 times more tolerant than CL 121 with 280 g/ha imazethapyr. In the conventional tillage and water-seeded system where soil was worked under flooded conditions one day prior to drainage, off-site movement of solids in the initial discharge of irrigation water was 1250 kg/ha. This compares with no more than 80 kg/ha for the initial drainage in reduced tillage systems where rice was water-seeded or drill-seeded. Total off-site movement of solids from initial drainage through 12 weeks totaled 2,370 kg/ha for the conventional tillage system and loss of solids was reduced by as much as 79% where reduced tillage systems were used.
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