Effect of 2,4-D on NR, NiR and Leghaemoglobin Synthesis in Root Nodules Formed by Bradyrhizobium japonicum in Glycine max.

The present study revealed that although very low concentrations (≤5μg/ml) of 2, 4-Dichlorophenoxyacetic acid (2, 4-D), a common herbicide, stimulated nitrate reductase (NR), nitrite reductase (NiR) and leghaemoglobin, in root nodules of Glycine max, higher cocentrations (>5μg/ml) were inhibitory. The results have also shown that treatment of rhizobia with different concentrations of 2, 4-D also affected NR and NiR of cytosol fraction of root nodules. This shows that there is a relationship between plant NR, NiR and the bacteroids in the root nodules.