HERBICIDES EFFECTS ON NODULATION, GROWTH AND NITROGEN YIELD OF FABA BEAN INDUCED BY INDIGENOUS RHIZOBIUM-LEGUMINOSARUM

The effect of the herbicides brominal (Bromoxynil: 20 % active ingredient, 3,5-dibromo-4-hydroxybenzonitrile) and Gramoxone (Paraquat: 24 % active ingredient, 1,1-dimethyl-4,4-bipyridylium dichloride) on the growth and symbiotic nitrogen fixation of Vicia faba was studied in pots. The herbicides were applied al rates of recommended field dose as well as 2 and 3 fold-field dose to unsterilized clay soil. All doses of herbicides significantly reduced the plant growth (dry matter), nodulation, total nitrogen and carbohydrate contents of shoot and roots. Protein, leghaemoglobin and carbohydrate contents of cytosol and bacteroid fractions ware significantly inhibited when plant treated with 2 and 3-fold recommended field dose. The results suggest that both herbicides act directly to the plant and indirectly on the nodule content.