Abstract: Laboratory studies were conducted to determine if electrolyte leakage from either leaf tissue, germinating seeds, or excised roots correlated with previously established soil-applied field response of soybean cultivars and target weeds to sulfentrazone. Sulfentrazone-induced electrolyte leakage from leaf tissue of coffee senna (sensitive), sicklepod (tolerant), and soybean cultivars ‘Asgrow 6785’ and ‘Carver’ (sensitive) and ‘Stonewall’ and ‘DPL 3606’ (tolerant) was monitored over time. Electrolyte leakage from leaf tissues, caused by 25 ppm (65 μM) sulfentrazone, agreed directly with the known response of these weeds, but response of the four soybean cultivars was equivalent. Furthermore, sulfentrazone-induced electrolyte leakage from leaf tissue of Asgrow 6785 and Stonewall was not affected by sulfentrazone concentration as high as 100 ppm (258 μM) nor by light intensity (4 and 120 μmol/m2/s photosynthetically active radiation). For germinating seeds, sulfentrazone-induced electrolyte leakage was also independent of soybean cultivar. In contrast, electrolyte leakage from excised roots of germinal soybean seedlings did concur directly with the previously established cultivar sensitivity to soil-applied sulfentrazone. Results indicate that electrolyte leakage from excised roots of soybean germinal seedlings can be used to assess cultivar sensitivity to soil-applied sulfentrazone.
Nomenclature: Sulfentrazone, coffee senna, Cassia occidentalis L. #3 CASOC; sicklepod, Senna obtusifolia L. # CASOB; soybean, Glycine max (L.) Merr. ‘Asgrow 6785’, ‘Carver’, ‘Stonewall’, ‘DPL 3606’.
Additional index words: Herbicide tolerance, membrane leakage, Protox, light intensity.
Abbreviations: Ie, index of relative electrolyte leakage; PAR, photosynthetically active radiation; Protogen, protoporphyrinogen; Proto IX, protoporphyrin; Protox, protoporphyrinogen oxidase.
