芨芨草叶片养分特征对氮磷不同添加水平的响应

植物叶片氮(N)、磷(P)养分特征受土壤可利用性N、P含量和N、P相对比例(N:P)的共同影响, 研究其作用机制有助于解释和评估土壤养分变化对植物养分利用策略的影响。该研究通过盆栽实验, 探讨芨芨草(Achnatherum splendens)养分化学计量学特征和叶片养分回收特征对不同剂量的养分添加(低、中、高3个N添加水平: 1.5、4.5、13.5 g·m^-2·a^-1)及不同土壤N:P (5、15、25)的响应。结果表明: 养分添加水平的提高显著增加了成熟叶片P含量和衰老叶片N、P含量, 显著降低了叶片N、P养分回收效率(NRE, PRE)。土壤N:P的升高显著降低了衰老叶片P含量和叶片NRE, 但增加了成熟和衰老叶片N:P和叶片PRE。相同养分添加水平条件下, 土壤N:P与叶片PRE显著正相关, 但与叶片NRE无显著相关性; 相同N:P条件下, 养分添加水平与NRE负相关, 但与PRE无显著相关性。植物NRE:PRE可以有效地反映环境变化所导致的植物对N、P需求的改变。土壤养分添加水平和N:P共同影响着芨芨草的叶片养分生态化学计量学特征和养分回收。

Response of nutrient characteristics of Achnatherum splendens leaves to different levels of nitrogen and phosphorus addition

Aims The nutrient characteristics of nitrogen (N) and phosphorus (P) in plant leaves are affected by soil available N, P contents and soil N:P. However, little is known about the effects of changes in soil N, P contents and N:P on N, P stoichiometry in leaves and nutrient resorption efficiency. Methods In this study, pot experiments were conducted to explore the response of the stoichiometry and nutrient resorption characteristics of Achnatherum splendens leaves to three levels of nutrient addition (low, 1.5 g·m^-2·a^-1; moderate, 4.5 g·m^-2·a^-1; and high, 13.5 g·m^-2·a^-1) and N:P (5, 15, 25). Important findings The results showed that higher level of nutrient addition significantly increased the P contents in green leaves and N, P contents in senescent leaves, but significantly deceased the N resorption efficiency (NRE) and P resorption efficiency (PRE). The increases in soil N:P significantly decreased the P contents in senescent leaves and NRE, but increased N:P in green and senescent leaves and PRE. At the same nutrient addition level, soil N:P was significantly positively correlated with PRE, but showed no significant correlation with NRE. At the same level of N:P, the level of nutrition addition was negatively correlated with NRE, but exhibited no significant correlation with PRE. The changes in plant demand for N and P caused by changing environment can be indicated effectively by plant leaf NRE:PRE, and the characteristics of nutrient stoichiometry and resorption of A. splendens leaves are affected together by nutrient addition levels and soil N:P.