Impact of rhizobial inoculation and reduced N supply on biomass production and biological N2 fixation in common bean grown hydroponically

Charis Konstantina Kontopoulou, Epifanios Liasis, Pietro P.M. Iannetta, Anastasia Tampakaki, Dimitrios Savvas*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

BACKGROUND: Testing rhizobial inoculation of common bean (Phaseolus vulgaris L.) in hydroponics enables accurate quantification of biological N2 fixation (BNF) and provides information about the potential of reducing inorganic N fertilizer use. In view of this background, common bean grown on pumice was inoculated with Rhizobium tropici CIAT899 (Rt) and supplied with either full-N (total nitrogen 11.2 mmol L−1), 1/3 of full-N or N-free nutrient solution (NS). BNF was quantified at the early pod-filling stage using the 15N natural abundance method. RESULTS: Full-N supply to Rt-inoculated plants resulted in markedly smaller nodules than less- or zero-N supply, and no BNF. Rt inoculation of full-N-treated plants did not increase biomass and pod yield compared with non-inoculation. Restriction (1/3 of full-N) or omission of inorganic N resulted in successful nodulation and BNF (54.3 and 49.2 kg N ha−1, corresponding to 58 and 100% of total plant N content respectively) but suppressed dry shoot biomass from 191.7 (full-N, +Rt) to 107.4 and 43.2 g per plant respectively. Nutrient cation uptake was reduced when inorganic N supply was less or omitted. CONCLUSION: Rt inoculation of hydroponic bean provides no advantage when full-N NS is supplied, while 1/3 of full-N or N-free NS suppresses plant biomass and yield, partly because the restricted NO3 supply impairs cation uptake.

Original languageEnglish
Pages (from-to)4353-4361
Number of pages9
JournalJournal of the Science of Food and Agriculture
Volume97
Issue number13
DOIs
Publication statusPublished - Oct 2017

Keywords

  • nitrogen
  • Phaseolus vulgaris
  • Rhizobium tropici
  • soilless culture
  • yield

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