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Effects of <sup>15</sup>N-nitrate fertilization on yield and dinitrogen fixation in common bean (<i>Phaseolus vulgaris</i> L.)
Abstract
The isotope dilution method was used to examine the influence of 15N-nitrate fertilizer on dinitrogen fixation and dry matter production in young common bean (Phaseolus vulgaris L.) plant in a phytotron experiment. There were slight variations in dry matter yield with significantly different N concentrations of the bean crop in response to fertilizer nitrogen applieation. The proportion of total N derived from N2 fixation in the vegetative plant parts decreased from 43.5 to 4.7 per cent as the rate of fertilizer nitrogen increased from 0 to 150 kg N/ha. However, the degree of inhibition of N2 fixation by applied nitrate-N was not different at the 75 and 150 kg N/ha rates. Inoculation did not affect the relative contributions of fertilizer and soil nitrogen to total shoot N at the 75 and 150 kg N/ha levels.