Reallocation of nitrogen and phosphorus from roots drives regrowth of grasses and sedges after defoliation under deficit irrigation and nitrogen enrichment,Journal of Ecology

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Reallocation of nitrogen and phosphorus from roots drives regrowth of grasses and sedges after defoliation under deficit irrigation and nitrogen enrichment
Journal of Ecology ( IF 5.3 ) Pub Date : 2021-09-04 , DOI: 10.1111/1365-2745.13778
Ruzhen Wang _{1,

2} , Tom Cresswell ₃ , Mathew P. Johansen ₃ , Jennifer J. Harrison ₃ , Yong Jiang ₁ , Claudia Keitel ₂ , Timothy R. Cavagnaro ₄ , Feike A. Dijkstra ₂

Affiliation

Reallocation of nutrients from roots to shoots is essential for plant regrowth in grasslands, particularly in nutrient-poor conditions. However, the response of root nutrient reallocation to changes in nitrogen (N) and water availability remains largely unknown.
Using a novel ¹⁵N and ³²P labelling technique, we quantified the contribution of N and phosphorus (P) to shoot regrowth from either root reallocation or direct soil uptake for perennial grasses exposed to high-frequency deficit irrigation (HFDI) and N addition.
Without N addition, HFDI showed no impact on uptake and reallocation 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 reallocation with N addition, possibly due to exhaustion of nutrient reserves in roots that were re-allocated above-ground. Reallocation contributed 48%–97% of N and 58%–79% of P required during the first 2 weeks of shoot regrowth.
Synthesis. Our results highlight the importance of N and P reallocation from roots to buffer against changes in soil N and P availability and to maintain N:P ratio in shoot regrowth.

中文翻译：

亏缺灌溉和富氮下落叶后根系氮和磷的重新分配驱动草和莎草的再生

将养分从根部重新分配到芽部对于草原植物的再生至关重要，尤其是在营养贫乏的条件下。然而，根系养分重新分配对氮 (N) 和可用水量变化的响应在很大程度上仍然未知。
使用新的¹⁵ N 和³² P 标记技术，我们量化了 N 和磷 (P) 对暴露于高频亏缺灌溉 (HFDI) 和 N 添加的多年生草根重新分配或直接土壤吸收的芽再生的贡献。
如果不添加 N，HFDI 对 N 和 P 的吸收和重新分配没有影响，这可能是由于土壤 N 的有效性未受影响，并且更大的扩散屏障抵消了植物可用土壤 P 中积累的增加。添加 N 后，HFDI 增加了植物 N 而不是 P吸收，因为在 HFDI 和 N 添加组合下增加了土壤 N 的有效性而不是 P。HFDI 通过添加 N 降低了 N 和 P 的重新分配，这可能是由于在地上重新分配的根中养分储备耗尽。在芽再生的前 2 周，重新分配贡献了 48%–97% 的 N 和 58%–79% 的 P。
合成。我们的结果强调了氮和磷从根部重新分配的重要性，以缓冲土壤氮和磷可用性的变化，并在芽再生中保持 N:P 比率。

更新日期：2021-09-04

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