It was hypothesized that Mn uptake efficiency and transport by transgenic, glifosate-resistant soybean would be affected by application of the herbicide. Two experiments were carried out to study manganese uptake, long-distance transport and absorption kinetics of genetically modified soybean as affected by glifosate application. Experiment 1: The treatments consisted of two near-isogenic soybean cultivars grown in nutrient solution (Conquista and Valiosa RR with or without application of glifosate). The Mn levels in the nutrient solution were 0, 0.085, 0.125, 0.250, 0.500 mg L-1. Twenty-five days after emergence, part of the total transgenic soybean plants were sprayed with herbicide. Experiment 2: Plants were sprayed with glifosate on the 26th day of cultivation at rates of 0 (zero), 15 and 960 g ha-1 to study the Mn absorption kinetics of cultivar Valiosa RR. It was found that genetic resistance to glifosate did not affect manganese nutrition in soybean cultivar Valiosa RR. Despite reducing the root dry matter, glifosate does not hamper Mn absorption and transport in transgenic soybean plants. The Mn absorption kinetic parameters of Valiosa RR, Km, Vmax and Cmin are not altered by glifosate applied to leaves.
Glycine max L.; absorption kinetics; micronutrients and plant nutrition
