Ehlting B, Dluzniewska P, Dietrich H, Selle A, Teuber M, Hänsch R, Nehls U, Polle A, Schnitzler J-P, Rennenberg H, Gessler A
Institut für Forstbotanik und Baumphysiologie, Professur für Baumphysiologie, Albert-Ludwigs-Universität Freiburg, Georges-Koehler-Allee 053/054, 79110 Freiburg, Germany.
Plant Cell Environ. 2007 Jul;30(7):796-811. doi: 10.1111/j.1365-3040.2007.01668.x.
Salinity represents an increasing environmental problem in managed ecosystems. Populus spp. is widely used for wood production by short-rotation forestry in fertilized plantations and can be grown on saline soil. Because N fertilization plays an important role in salt tolerance, we analysed Grey poplar (Populus tremula x alba, syn. Populus canescens) grown with either 1 mM nitrate or ammonium subjected to moderate 75 mM NaCl. The impact of N nutrition on amelioration of salt tolerance was analysed on different levels of N metabolism such as N uptake, assimilation and N (total N, proteins and amino compounds) accumulation. Na concentration increased in all tissues over time of salt exposure. The N nutrition-dependent effects of salt exposure were more intensive in roots than in leaves. Application of salt reduced root increment as well as stem height increase and, at the same time, increased the concentration of total amino compounds more intensively in roots of ammonium-fed plants. In leaves, salt treatment increased concentrations of total N more intensively in nitrate-fed plants and concentrations of amino compounds independently of N nutrition. The major changes in N metabolism of Grey poplar exposed to moderate salt concentrations were detected in the significant increase of amino acid concentrations. The present results indicate that N metabolism of Grey poplar exposed to salt performed better when the plants were fed with nitrate instead of ammonium as sole N source. Therefore, nitrate fertilization of poplar plantations grown on saline soil should be preferred.
盐分是人工管理生态系统中日益严重的环境问题。杨树被广泛用于短轮伐期林业的木材生产，可种植于施肥的人工林中，也能在盐碱地上生长。由于氮肥在耐盐性方面起着重要作用，我们分析了在施加75 mM NaCl中度胁迫条件下，分别以1 mM硝酸盐或铵盐为氮源培养的灰杨（Populus tremula x alba，同物异名Populus canescens）。从氮吸收、同化以及氮（总氮、蛋白质和氨基化合物）积累等不同氮代谢水平，分析了氮营养对耐盐性改善的影响。随着盐分暴露时间的延长，所有组织中的钠浓度均升高。盐分暴露对氮营养的依赖性影响在根部比在叶片中更为强烈。施加盐分降低了根的生长增量以及茎的增高，同时，在以铵盐为氮源的植株根部，总氨基化合物的浓度升高更为强烈。在叶片中，盐分处理使以硝酸盐为氮源的植株中总氮浓度升高更为强烈，而氨基化合物的浓度升高则与氮营养无关。暴露于中度盐分浓度下的灰杨，其氮代谢的主要变化表现为氨基酸浓度显著增加。目前的结果表明，当以硝酸盐而非铵盐作为唯一氮源时，暴露于盐分环境中的灰杨氮代谢表现更佳。因此，对于种植在盐碱地上的杨树人工林，应优先选择硝酸盐施肥。
