Barea J M, Azcón-Aguilar C, Azcón R
Departamento de Microbiologia, Estación Experimental del Zaidin, C.S.I.C. Prof. Albareda 1, 18008-Granada, Spain.
New Phytol. 1987 Aug;106(4):717-725. doi: 10.1111/j.1469-8137.1987.tb00172.x.
A technique using N-labelled inorganic fertilizer was applied to estimate N fixation by the forage legume Hedysarum coronarium L. and to ascertain the role of vesicular-arbuscular (VA) mycorrhizas in plant N nutrition throughout a growing season under field conditions. The absence of the specific Rhizobium for the forage legume in the test soil allowed us the use of N methodology with the same legume as reference 'non-fixing' crop. At the first harvest, mycorrhizal inoculation behaved similarly to the phosphate addition in improving the percentage (70 %) and the total amount of N derived from fixation. But thereafter, mycorrhizal inoculation not only enhanced dry matter yield, N concentration and total N yield but also the amount of N derived from soil and from fixation, as compared with either phosphate-added or control plants. This indicated that mycorrhizas acted both by a P-mediated mechanism to improve N fixation and by enhancing N uptake from soil. The latter agrees with recent findings by others that VA mycorrhizal hyphae can translocate and assimilate ammonium, a fact of physiological and ecological interest.
采用一种使用氮标记无机肥料的技术来估算豆科牧草冠状岩黄芪（Hedysarum coronarium L.）的固氮量，并确定在田间条件下整个生长季节泡囊丛枝（VA）菌根在植物氮营养中的作用。试验土壤中缺乏该豆科牧草的特定根瘤菌，这使我们能够将同一豆科植物作为参考“非固氮”作物来使用氮方法。在第一次收获时，菌根接种在提高固氮百分比（70%）和固氮总量方面的表现与添加磷肥相似。但此后，与添加磷肥或对照植株相比，菌根接种不仅提高了干物质产量、氮浓度和总氮产量，还增加了来自土壤和固氮的氮量。这表明菌根既通过磷介导机制促进固氮，又通过增强从土壤中吸收氮来发挥作用。后者与其他人最近的研究结果一致，即VA菌根菌丝可以转运和同化铵，这是一个具有生理和生态意义的事实。
