Response of Selected Soybean (Glycine max) Cultivars to Dimethenamid and Metolachlor in Hydroponic Conditions

Soybean cultivars were grown in a hydroponic culture to evaluate tolerance to dimethenamid and metolachlor. Root length was reduced in 7 of the 32 cultivars with 50 ppb dimethenamid. ‘Asgrow 5403’ and ‘Bryan’ root lengths were reduced more than 20%. ‘Asgrow 6297’ was the only cultivar with greater than 12% root length reductions with 83 ppb metolachlor. The longest lateral root of all cultivars was shortened with dimethenamid. ‘NK-1460’ and Bryan expressed the most lateral root length reduction, at 73 and 62%, respectively. Asgrow 6297 was tolerant to dimethenamid, but lateral roots were reduced 16%. Metolachlor reduced the lateral root lengths of 12 cultivars, with Asgrow 5403, ‘Coker 6955,’ and Bryan reduced more than 20%. Bryan was the most sensitive cultivar to both herbicides, while ‘Brim’ was the most tolerant of cultivars evaluated.