Re-allocation of nitrogen and phosphorus from roots drives regrowth of grasses and sedges after defoliation under deficit irrigation and nitrogen enrichment
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Date
2021-09-04
Journal Title
Journal ISSN
Volume Title
Publisher
John Wiley & Sons, Inc
Abstract
1. Re-allocation of nutrients from roots to shoots is essential for plant regrowth in grasslands, particularly in nutrient-poor conditions. However, the response of root nutrient re-allocation to changes in nitrogen (N) and water availability remains largely unknown.
2. Using a novel 15N and 32P labelling technique, we quantified the contribution of N and phosphorus (P) to shoot regrowth from either root re-allocation or direct soil uptake for perennial grasses exposed to high-frequency deficit irrigation (HFDI) and N addition.
3. Without N addition, HFDI showed no impact on uptake and re-allocation of N and P, likely due to unaffected soil N availability and a greater diffusion barrier offsetting increased accumulation in plant-available soil P. With N addition, HFDI increased plant N rather than P uptake, because of increasing soil N availability instead of P under combined HFDI and N addition. The HFDI decreased both N and P re-allocation with N addition, possibly due to exhaustion of nutrient reserves in roots that were re-allocated aboveground. Re-allocation contributed 48-97% of N and 58-79% of P required during the first two weeks of shoot regrowth.
4. Synthesis. Our results highlight the importance of N and P re-allocation from roots to buffer against changes in soil N and P availability and to maintain N:P ratio in shoot regrowth. © 2021 British Ecological Society
Description
The attached PDF is the postprint version which had undergone full peer review but had not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record.
Keywords
Irrigation, Soils, Plants, Roots, Biomass, Nitrogen, Phosphorus, Nutrients, Water, Isotopes, Labelling
Citation
Wang, R., Cresswell, T., Johansen, M. P., Harrison, J. J., Jiang, Y., Keitel, C., Cavagnaro, T. R. & Dijkstra, F. A. (2021) Re‐allocation of nitrogen and phosphorus from roots drives regrowth of grasses and sedges after defoliation under deficit irrigation and nitrogen enrichment. Journal of Ecology, 109(12), 4071-4080. doi:10.1111/1365-2745.13778