Date of Graduation

8-2022

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor

Jason Norsworthy

Committee Member

Thomas Butts

Second Committee Member

Trenton Roberts

Third Committee Member

Edward Gbur

Keywords

Air temperature, environmental conditions, light intensity, quizalofop-resistant rice, rice injury, soil moisture content

Abstract

Quizalofop-resistant rice technology allows for over-the-top applications of quizalofop, an acetyl-coenzyme A carboxylase-inhibiting herbicide. However, quizalofop caused significant injury to quizalofop-resistant rice in some Arkansas fields during the first year of commercialization. Experiments evaluated the effect of early-season soil moisture and nitrogen availability; pre-exposure to low rates of glyphosate and imazethapyr; planting date; and environmental conditions including, soil moisture content, air temperature, and light intensity on quizalofop-resistant rice tolerance to quizalofop applications. All experiments assessed sequential quizalofop applications made to 2-leaf followed by 5-leaf stage of rice. Sequential quizalofop applications alone and with surface irrigation or nitrogen application at the 2-leaf rice stage after the initial herbicide application caused minimal injury to quizalofop-resistant cultivars, with

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