Soybean (Glycine max) Cultivar Tolerance to Chlorimuron and Imazaquin with Varying Hydroponic Solution pH

Abstract

Twenty determinate soybean cultivars were grown in hydroponic solutions to determine differential tolerance to chlorimuron and imazaquin at pH 6, 7, or 8. ‘Epps' exhibited tolerance to chlorimuron at each pH, and to imazaquin except at pH 8. ‘9641 Pioneer’ was highly sensitive to both herbicides at each pH, and ‘Asgrow 5979’ was sensitive to chlorimuron, and to imazaquin except at pH 7. ‘Hutcheson’ was sensitive to chlorimuron at each pH, and imazaquin at pH 6. ‘Asgrow 6785’ was sensitive to chlorimuron at pH 6 and 8, with shoot weight reductions of 31 and 28%, respectively, and ‘Coker 686’ was similarly sensitive at pH 6 and 7. ‘Hartz 6200’ was tolerant to imazaquin at pH 6 and 7, ‘Hartz 6686’ was tolerant at pH 6 and 8, and Coker 686 was tolerant at pH 7 and 8. Coker 686 and 'Sharkey’ were tolerant to chlorimuron at some pH levels, though highly sensitive at other pH levels. ‘Asgrow 5403’ and Coker 686 also had varying tolerance and sensitivity to imazaquin across pH levels. Shoot length and shoot weight were the best indicators of differential cultivar sensitivity when compared with previous field studies.