陆地生态系统植物吸收有机氮的研究进展

Research progress on the uptake of organic nitrogen by terrestrial plants

在一些强烈受到氮矿化限制的地区如北极苔原、高山草甸和北方森林,很多植物可以吸收土壤中的有机氮。这种现象引起人们对建立于氮矿化基础上的陆地生态系统氮循环模式的重新思考。本文主要就植物可吸收利用土壤中有机氮的类型,菌根在植物养分获取过程中扮演的角色,以及有机氮吸收的试验设计方法等进行综述。研究发现,植物可直接吸收的土壤有机氮主要包括游离氨基酸和小分子肽。在植物从复杂氮源如蛋白质、几丁质和多酚-蛋白质络合物获取养分的过程中,菌根真菌和腐生真菌的作用不容忽视。植物吸收有机氮的试验设计可以借助同位素技术和数学模型等方法,如何使试验能够真实地反映植物在自然条件下对有机氮吸收的能力是在未来的研究中需要仔细考虑的问题。

In some ecosystems such as arctic tundra,alpine meadow and boreal forest where nitrogen mineralization is strongly limited,it is found that many plants are able to directly absorb organic nitrogen(N)in soil.This phenomenon urges people to rethink the traditional concept of terrestrial N cycling based on N mineralization.In this review,we analyze the recent work about the types of organic N that plants can absorb,the roles of mycorrhiza in these nutrition-acquiring processes and experimental designs and methods utilized in theses studies.The organic N sources that plants can absorb include free amino acids and low molecular weight peptides.The roles of mycorrhizal fungi and saprotrophic fungi are important during the process of obtaining N sources in polyphenol-protein complexes by plants.The design of organic N uptake experiments could be performed with the help of isotope techniques and mathematic models.In the future,how to examine the uptake of organic N by plants under field conditions needs to be carefully considered in research.