Thomas Frank M, Sprenger Susanne
Georg-August-Universität Göttingen, Institute for Plant Sciences, Department of Plant Ecology, Untere Karspüle 2, 37073 Göttingen, Germany.
Tree Physiol. 2008 Mar;28(3):343-53. doi: 10.1093/treephys/28.3.343.
Quercus robur (L.) and Q. petraea (Matt.) Liebl. are European oak species that often grow in forest soils with high soluble manganese (Mn2+) concentrations. We tested the effects of Mn2+ at concentrations of 0.0024 mM (control), 0.24 mM (typical of acidic forest soils) and 1.2 mM (typical of forest soils under strongly reducing conditions) on the growth, tissue anatomy, foliar element concentrations, subcellular element distribution and gas exchange of solution-cultured seedlings. At the highest Mn2+ concentration, seedlings were grown with and without an elevated concentration (1.2 mM) of magnesium (Mg2+). At 0.24 mM Mn2+, foliar Mn concentrations were higher than observed in the field. Vacuoles of the leaf epidermis and mesophyll were the main sites of manganese accumulation. High nutrient solution Mn2+ concentration significantly lowered foliar iron (Fe) and Mg concentrations. Elevated Mg2+ concentration raised the foliar Mg concentrations to control values, but Fe concentrations and gas exchange remained depressed. In seedlings grown in the 1.2 mM Mn2+ treatment without elevated Mg2+ damage to the phloem of the petioles and a reduction in root mass were observed in both species. The effects on shoot and root growth were greatest in Q. petraea. Alleviation of manganese toxicity symptoms by Mg2+ in Q. petraea was less effective than in Q. robur. Our results suggest that the soil solution Mn2+ concentrations that occur in European oak forests are unlikely to affect the distribution and performance of Q. robur and Q. petraea in the field.
欧洲栓皮栎（Quercus robur (L.)）和无梗花栎（Q. petraea (Matt.) Liebl.）是欧洲栎树种，常生长于可溶性锰（Mn2+）浓度较高的森林土壤中。我们测试了浓度为0.0024 mM（对照）、0.24 mM（酸性森林土壤典型浓度）和1.2 mM（强还原条件下森林土壤典型浓度）的Mn2+对溶液培养幼苗的生长、组织解剖结构、叶片元素浓度、亚细胞元素分布和气体交换的影响。在最高Mn2+浓度下，幼苗分别在添加和不添加高浓度（1.2 mM）镁（Mg2+）的条件下生长。在0.24 mM Mn2+浓度下，叶片锰浓度高于田间观测值。叶片表皮和叶肉的液泡是锰积累的主要部位。高营养液Mn2+浓度显著降低了叶片铁（Fe）和镁浓度。提高Mg2+浓度可使叶片镁浓度恢复到对照值，但铁浓度和气体交换仍受到抑制。在1.2 mM Mn2+处理且未提高Mg2+浓度的情况下生长的幼苗，两个树种均出现叶柄韧皮部受损和根质量下降的情况。对地上部和根系生长的影响在无梗花栎中最为显著。Mg2+对无梗花栎锰毒性症状的缓解效果不如欧洲栓皮栎。我们的结果表明，欧洲橡树林中土壤溶液的Mn2+浓度不太可能影响欧洲栓皮栎和无梗花栎在田间的分布和表现。
