Effects of excess nitrogen on carbohydrate concentration and mycorrhizal development of Pinus sylvestris L. seedlings
Effects of excess nitrogen on carbohydrate concentration and mycorrhizal development of Pinus sylvestris L. seedlings
复制标题
过量施氮对樟子松幼苗碳水化合物浓度及菌根发育的影响
DOI：
10.1111/j.1469-8137.1991.tb00040.x
复制
发表时间：
1991
期刊：
影响因子：
9.4
通讯作者：
J. Nylund
中科院分区：
文献类型：
--
作者：
H. Wallander;J. Nylund
总结
氮供应、碳水化合物可用性和外生菌根的相互作用已成为多项研究的主题，并被解释为共生的调节机制。只有少数研究同时研究了外部氮供应对内部氮浓度、内部糖库以及定量菌根定殖程度的影响。后者通常仅通过根尖计数来估计，准确性较低。
使用麦角甾醇作为真菌生物量的定量描述符，在半水培栽培系统中重新检验了碳水化合物理论的几个基本假设，其中含有 Laccaria bicolor (Maire) Orton 的赤松幼苗菌根在基于补充有过量铵或硝酸盐的平衡基础培养基的营养方案上以大致恒定的相对生长速率生长。菌根生物量与地上部氮密切相关。高氮利用率并没有显着影响内部糖浓度。菌根的发育显着降低了根和芽中的糖浓度。铵盐和硝酸盐在减少菌根发育方面的差异是由于单独吸收的差异造成的。这些发现往往会推翻碳水化合物理论的基本假设，即高氮利用率导致糖浓度降低，后者限制了菌根的发育。该结果也与菌根存在时宿主糖浓度升高的观点相矛盾。
summary
The interaction of nitrogen supply, carbohydrate availability and ectomycorrhiza has been the subject of several studies and has been interpreted as the regulatory mechanism of the symbiosis. Only a few studies have simultaneously examined the effect of external nitrogen supply on the internal concentration of N, the internal sugar pool and, in a quantitative way, the extent of mycorrhizal colonization. The latter has usually been estimated with low accuracy through root tip counting only.
Using ergosterol as a quantitative descriptor of fungal biomass, several of the basic assumptions of the carbohydrate theory have been re examined in a semi-hydroponic cultivation system, where Scots pine seedlings mycorrhizal with Laccaria bicolor (Maire) Orton were grown at an approximately constant relative growth rate on a nutrition regime based on a balanced basic medium supplemented with excess ammonium or nitrate. Mycorrhizal biomass was strongly correlated with the shoot nitrogen. High nitrogen availability did not significantly affect internal sugar concentrations. The development of mycorrhiza significantly reduced sugar concentrations in both roots and shoots. The difference between ammonium and nitrate in reducing mycorrhizal development was due to differences in uptake alone. The findings tend to invalidate a basic assumption of the carbohydrate theory, that of high nitrogen availability leading to reduced sugar concentration, the latter limiting mycorrhizal development. The results also conflict with the view that the host's sugar concentration is elevated in the presence of mycorrhiza.