Phosphorus modifies the effects of nitrogen on nodulation in split-root systems of Hippophaë rhamnoides

Authors

  • Francesco Gentili,

    Corresponding author
    1. Department of Agricultural Research for Northern Sweden, Crop Science Section, Swedish University of Agricultural Sciences, Box 4097, S-904 03 Umeå, Sweden
      Author for correspondence: Francesco Gentili Tel: +46 90 7869410 Fax: +46 90 7869404 Email: Francesco.Gentili@njv.slu.se
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  • Kerstin Huss-Danell

    1. Department of Agricultural Research for Northern Sweden, Crop Science Section, Swedish University of Agricultural Sciences, Box 4097, S-904 03 Umeå, Sweden
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Author for correspondence: Francesco Gentili Tel: +46 90 7869410 Fax: +46 90 7869404 Email: Francesco.Gentili@njv.slu.se

Summary

  •  The effects of N (ammonium nitrate), P (phosphate) and their interactions on nodulation were studied in the intercellularly infected actinorhizal plant Hippophaë rhamnoides.
  •  A split-root design, with pots receiving different concentrations of N and P, was used to determine whether the effects of N and P are local or systemic, if they are specific to nodulation or general, and whether P could counteract N inhibition. H. rhamnoides plants were grown for 6–10 wk after inoculation with Frankia.
  •  Inhibition of nodulation by N was systemic for both nodule number and nodule biomass in H. rhamnoides.
  •  By contrast, high P had a systemic stimulation on nodule number and biomass and P prevented systemic, but not local, N inhibition. Stimulation by P was specific to nodulation and not simply mediated via plant growth. Whether N and P alter not only nodulation but also N2-fixation in the nodules requires further investigation.

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