Abstract
Purpose: Belowground carbon (C) allocation for nitrogen (N) acquisition plays a crucial role in determining primary productivity and plant competitiveness in legume-grass mixtures, but beyond modeling and qualitative assessments, this remains poorly understood, especially with regard to drought stress and interspecific interactions.
Methods: We grew a legume (Trifolium repens) and a grass (Lolium perenne) in monocultures and as a 50:50 mixture (with same plant density), at 70% and 50% soil water holding capacity representing non-drought and drought conditions, for 104 days in a growth chamber experiment. By using continuous 13CO2 labelling and 15N pulse soil-labelling, we analyzed how drought and interspecific interaction affected belowground C allocation (including root biomass, root respiration and rhizodeposition) and N acquisition through soil N uptake and biological N fixation.
Results: Drought increased belowground C allocation per unit of N acquisition in the legume, but not in the grass. Drought significantly reduced biological N fixation in the legume, so that the legume allocated relatively more C to take up soil N. Interspecific competition increased belowground C allocation per unit of N acquisition, which could be attributed to a reduction in biological N fixation by the legume and an increased abundance of the grass.
Conclusions: We highlight that drought and interspecific competition for N strongly alter C allocation towards biological N fixation and soil N uptake. Our measurements provide important process-based information to improve modeling drought effects on productivity and composition in legume-grass mixtures.
Original language | English |
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Pages (from-to) | 269-283 |
Number of pages | 15 |
Journal | Plant and Soil |
Volume | 481 |
Issue number | 1-2 |
Early online date | 3 Aug 2022 |
DOIs | |
Publication status | Published - Dec 2022 |
Externally published | Yes |
Keywords
- 13C tracer
- 15N tracer
- Biological nitrogen fixation
- Rhizodeposition
- Root biomass
- Root respiration
- Water stress