Nutrient resorption exacerbates nitrogen–phosphorus imbalances in plants under increasing nitrogen addition in a saline–alkaline grassland

作者：Yuan Su, Shuaikai Wu, Jie Hao, Huajie Diao, Kuanhu Dong, Changhui Wang · 发表于：Journal of Plant Ecology · 年份：2024 · DOI：10.1093/jpe/rtad049 · 被引用次数：2 · 研究领域：Soil and Water Nutrient Dynamics、Soil Carbon and Nitrogen Dynamics、Plant nutrient uptake and metabolism

Abstract Reabsorbing nutrients from senescent tissues before leaf falling has been recognized as a strategy to adapt to nutrient deficiency. However, how nutrient resorption modulates the nitrogen (N)–phosphorus (P) balance inside plants remains unclear, especially under increased soil N availability. We examined the impacts of N addition at varying rates (0–32 g N m−2 yr−1) on nutrient resorption and the performance of nutrient resorption on controlling the internal N–P balance in the leaf and stem of a dominant grass species, Leymus secalinus, in a saline–alkaline grassland in northern China. After 6 years of N addition, N concentration and N:P ratio in green and senesced tissues (leaf and stem) rose with increasing N addition. The P concentration in green tissues decreased, but did not significantly change in senesced tissues with increasing N addition. The N resorption efficiency (NRE), P resorption efficiency (PRE), and NRE:PRE ratio significantly decreased along the N addition gradient. Moreover, we found more sensitive responses of N:P ratio in senesced tissues than in green tissues; such exacerbation of plant internal N–P imbalances mainly resulted from a disproportionate reduction in nutrient resorption, especially NRE. Overall, our study suggested that differences in NRE and PRE further exacerbated the internal N–P imbalances in plant litters.