Leaf chlorophyll concentration and nitrogen content in soybean plants treated with herbicides

Abstract

Under greenhouse condition an experiment was carried out to evaluate trifluralin, chlorimuron and clomazone effects on nitrogen content and chlorophyll concentration in soybeans (Glycine max (L.) Merr. cv Uberlandia), throughout the plant cycle. The samples were collected at 14-day intervals being the first sample collected at 14 days after emergence. Herbicides affected N concentration of plant parts only during the vegetative growth stages of soybeans. Trifluralin and clomazone applications reduced N concentrations in the stems, leaves and roots. Chlorimuron, however, tended to increase leaf and nodule N concentrations. Pod, pod wall and seed N concentrations were not influenced by the herbicides. Leaves, stems and roots had greater N concentrations at the beginning of the vegetative cycle. There were no effects of herbicides on chlorophyll concentrations. It was estimated that the soil gained 4.7 g/m2 of N during the plant cycle, as result of nitrogen fixation.