Nodulation and nitrogen fixation of field grown common bean (Phaseolus vulgaris) as influenced by fungicide seed treatment

A field experiment was conducted at Bel Air station, in Dakar using 15N isotope dilution technique and the non nodulating soybean (Glycine max) variety m129 as reference plant to test the compatibility of Dichlorofenthion-thiram (DCT) fungicide to the inoculation of common bean (Phaseolus vulgaris) Paulista variety with both Rhizobium etli ISRA 353 and R. tropici strain ISRA 554. Nodulation was not induced with R. etliISRA 353 and nitrogen fixation did not occur. With R. tropici ISRA 554, a decrease in nodulation was observed, but nitrogen fixation was not significantly different compared to that of the non DCT-treated common bean.   Key words: Common bean, fungicides, isotope dilution, 15N, nitrogen fixation, nodulation, Phaseolus vulgaris, Rhizobium.