Seasonal uptake and allocation of phosphorus in Eriophorum vaginatum L measured by labelling with 32 P.
Seasonal uptake and allocation of phosphorus in Eriophorum vaginatum L measured by labelling with 32 P.
复制标题
通过 32 P 标记测量 Eriophorum vaginatum L 中磷的季节性吸收和分配。
作者：
S. Jonasson;F. S. Stuart Chapin
对形成草丛的莎草 Eriophorum vaginatum L. 中磷 (P) 库的季节性测量表明，每年的磷吸收量较低，但春季磷从地下储存到生长生物量的通量明显，秋季又恢复。早春和仲夏向草丛中添加 32 P 证实了这一推论。添加 32 P 导致几天内约 10% 的标记 P 快速掺入分蘖中。随后的吸收可以忽略不计，可能是因为未立即吸收的 32 P 被固定在土壤中并且无法被植物吸收。这表明营养脉冲在支持枇杷对磷的吸收方面比稳态矿化更重要。添加 32 P 后，根部最初保留了吸收的 32 P 总量的 60%。在接下来的几周内，部分 32 P 缓慢运输到茎基部和叶鞘，这是主要的储存器官。较低比例被输送至叶片。我们认为，养分的储存和再循环是正常田间条件下 E. vaginatum 生长的年度养分供应的主要来源，其中土壤中的磷固定和磷向根部扩散的低速率限制了土壤对磷的吸收，除了脉冲释放期间外。
Seasonal measurements of phosphorus (P) pools in the tussock-forming sedge Eriophorum vaginatum L. indicated low annual P uptake, but pronounced fluxes of P to growing biomass from below-ground stores in spring, and a return in autumn. Additions of 32 P to tussocks in early spring and mid summer confirmed this deduction. Addition of 32 P caused a rapid incorporation of about 10% of the labelled P in the tillers within a few days. Subsequent uptake was negligible, presumably because the 32 P not immediately absorbed was fixed in the soil and unavailable to plants. This demonstrates that nutrient pulses were more important than steady-state mineralization in supporting P uptake by Eriophorum vaginatum. After the 32 P additions, roots initially retained 60% of the total 32 P taken up. During the following weeks, part of the 32 P was transported slowly to stem bases and leaf sheaths, the principal storage organs. A lower proportion was transported to the leaf blades. We suggest that storage and recirculation of nutrients are the main sources of the annual nutrient supply to growth of E. vaginatum under normal field conditions, where P fixation in the soil and low rate of P diffusion towards the roots limit P uptake from soil except during periods of pulsed release.