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Enhancement of rhizosphere citric acid and decrease of NO3−/NH4+ ratio by root interactions facilitate N fixation and transfer.
- Source :
-
Plant & Soil . Feb2020, Vol. 447 Issue 1/2, p169-182. 14p. 1 Diagram, 1 Chart, 5 Graphs. - Publication Year :
- 2020
-
Abstract
- Aims: Cereal can stimulate legume N fixation through competition for soil mineral N. In addition, organic acids in the rhizosphere can mobilize external nutrients, which may help nodulation. However, how much NO3− and NH4+ competition and organic acids in the rhizosphere of intercropped crops contribute to N fixation remains unclear and requires study. Methods: Field and greenhouse experiments were conducted to quantify effects of N competition and organic acids on N fixation in a maize/alfalfa intercropping system. Results: Intercropping increased nitrogen derived from the atmosphere (%Ndfa), nodules number, and leghemoglobin content by 43.66%, 85.53%, 141.05%, respectively, leading to significantly improved total N uptake and yield, compared to monoculture. The improved %Ndfa was not only due to the depletion of NO3−, but also significantly correlated with the decrease of NO3−/NH4+ ratio and the increase of citric acid in rhizosphere of alfalfa, which could mobilize soluble resources for N fixation under no N addition. Overall, 15.4%–21.5% of N fixed by alfalfa was transferred to associated maize, and the improved N fixation enhanced N transfer. Conclusions: Our findings provide a mechanism for how root interactions facilitate N fixation, highlighting the importance of NO3−/NH4+ ratio and citric acid in nutrient mobilization for N fixation. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0032079X
- Volume :
- 447
- Issue :
- 1/2
- Database :
- Academic Search Index
- Journal :
- Plant & Soil
- Publication Type :
- Academic Journal
- Accession number :
- 142141727
- Full Text :
- https://doi.org/10.1007/s11104-018-03918-6