Effect of glyphosate on nutrient contents in glyphosate-resistant soybeans.

Although GR soybean technology is spread all over the countries involved in soybean production, there is no particular fertilizing recommendation under glyphosate use and not much has been reported in the influence of glyphosate on GR soybean status. The objective of this work was to evaluate the mineral status of GR soybeans and their non-GR parental lines under glyphosate use. Considering different soil types and cultivar maturity groups, a significative decrease in macro and micronutrients leaf contents and in photosynthetic parameters (chlorophyll, photosynthetic rate, transpiration and stomatal conductance) was observed under glyphosate use (single or sequential application), both when compared to their respective non GR parental lines and GR soybeans not submitted to glyphosate use. Shoot and root dry biomass productions were affected by glyphosate presence for all cultivars evaluated in both soils, probably because of a sum of effects: decrease of photosynthetic parameters, nutrient uptake and content into the plants.