The biological N fixation provided by diazotrophic bacteria may be an alternative for corn production in more sustainable or low-input agricultural systems. Therefore, this study aimed to evaluate the interactive effect of seed inoculation with Herbaspirillum seropedicae and nitrogen fertilization on the nitrogen use efficiency of different corn genotypes, through the technique of isotopic dilution of 15N. The experiment was carried out under controlled conditions in a greenhouse using a completely randomized design in a 3 × 2 × 2 factorial scheme with three corn hybrids: Maximus, P3646H and BRS3035, using inoculated and non-inoculated plants with two nitrogen doses (0.0 and 80 kg ha-1) and four replicates. At 35 days after emergence plants were collected, divided into root and shoots and analyzed with regard to root and shoot dry matter production, accumulated N in plant, N percentage and content coming from the fertilizer and use efficiency of N applied as a fertilizer. Results showed that there is a difference between corn genotypes concerning shoot dry matter production and percentage of N shoot coming from the fertilizer. Shoot dry matter production is influenced by H. seropedicae inoculation. This inoculation coupled with nitrogen fertilization promotes shoot N increments of about 32 and 62% for the hybrids P3646H and BRS3035, respectively. These hybrids showed increases of 34.3 and 64.4%, respectively, in N use efficiency when inoculated with H. seropedicae without the addition of N, what allows inferring that the BNF behaves as an important source of N to the system.
Key words: Zea mays L., diazotrophic bacteria, 15N, nitrogen fertilization.
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