J Plant Ecol ›› 2024, Vol. 17 ›› Issue (1): rtad049.DOI: 10.1093/jpe/rtad049

• Research Articles •    

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

Yuan Su1, 2, Shuaikai Wu1, 2, Jie Hao1, 2, Huajie Diao1, 2, Kuanhu Dong1, 2, *, Changhui Wang1, 2, *   

  1. 1Shanxi Key Laboratory of Grassland Ecological Protection and Native Grass Germplasm Innovation, College of Grassland Science, Shanxi Agricultural University, Taigu 030801, China;
    2Youyu Loess Plateau Grassland Ecosystem National Research Station, Shanxi Agricultural University, Taigu 030801, China

养分回收加剧了氮沉降背景下盐渍化草地优势植物内在氮磷的失衡

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.

Key words: ecological stoichiometry, nitrogen addition, nitrogen-phosphorus imbalance, resorption efficiency, resorption proficiency, resorption ratio, saline-alkaline grassland

摘要:
在落叶之前,从衰老组织中重新吸收养分被认为是植物适应养分缺乏的一种策略。然而,养分重吸收如何调节植物体内氮(N)和磷(P)的平衡仍不清楚,特别是在土壤氮有效性增加的情况下。本文研究了不同速率(0、1、2、4、8、16、24 和32 g N m-2 yr-1)氮添加对中国北方盐渍化草地优势植物赖草(Leymus secalinus)叶片和茎秆养分回收的影响,以及养分回收在调控植物内部氮磷平衡的作用。研究结果表明:氮添加6年后,随着施氮量的增加,绿色和衰老组织(叶和茎)的N浓度和氮磷比均呈上升趋势。随着施氮量的增加,绿色组织中P浓度降低,而衰老组织中P浓度无显著变化。N重吸收效率(NRE)、P重吸收效率(PRE)和NRE:PRE比值沿N添加梯度显著降低。此外,我们发现衰老组织(叶和茎)氮磷比比绿色组织(叶和茎)氮磷比对氮素添加的响应更敏感,植物内在氮磷失衡的加剧主要是由于不成比例的减少养分重吸收,尤其是NRE。总的来说,我们的研究表明,NRE和PRE的差异进一步加剧了植物凋落物内部氮磷的失衡。

关键词: 生态化学计量学, 氮添加, 氮磷失衡, 重吸收效率, 重吸收能力, 重吸收比, 盐渍化草地