Faculty of Forestry, University of Chile, P.O. Box 9206, Santiago, Chile.
Tree Physiol. 2009 Jul;29(7):857-68. doi: 10.1093/treephys/tpp030. Epub 2009 May 14.
Carbon (C) flux and partitioning responses of Pinus radiata (D. Don) clones to a factorial combination of nitrogen (N) and phosphorus (P) supply were estimated in small trees growing in a greenhouse over 44 weeks. Our objective was to use a C budget approach at the plant level to examine how a factorial combination of N and P additions and genotype modify gross primary production (GPP), net primary production (NPP), absolute C fluxes apportioned to aboveground net primary production (ANPP), aboveground plant respiration (APR), total belowground carbon flux (TBCF) and the partitioning of GPP to ANPP, APR and TBCF. Single N or P additions increased plant NPP and GPP similarly, but their combined effects exceeded those of their individual contributions. Nitrogen and to a lesser extent P additions enhanced carbon-use efficiency (CUE, NPP:GPP) and C partitioning to ANPP at the expense of TBCF. The fraction of GPP partitioned to APR was invariant to N or P additions. The ratio of soil respiration (FS) to TBCF was significantly greater in the low-N low-P addition treatment (61%) than in those treatments with single or combined N and P additions (49%). The slowest growing clone partitioned a significantly smaller fraction of GPP to ANPP (29%) than one of the faster-growing genotypes (33%). This research provides insight into how N and P regulate the C fluxes and partitioning in individual plants. Our results contribute to explaining clonal variation in aboveground growth rates and suggest that greater gains in CUE and partitioning to ANPP occur with addition of N rather than P supply.
在温室中生长了 44 周的小树上，估计了辐射松（D. Don）无性系对氮（N）和磷（P）供应的因子组合的碳（C）通量和分配响应。我们的目标是使用植物水平的 C 预算方法来研究 N 和 P 添加物的因子组合以及基因型如何改变总初级生产力（GPP）、净初级生产力（NPP）、分配给地上净初级生产力（ANPP）的绝对 C 通量、地上植物呼吸（APR）、总地下碳通量（TBCF）以及 GPP 到 ANPP、APR 和 TBCF 的分配。单一的 N 或 P 添加物同样增加了植物的 NPP 和 GPP，但它们的综合效应超过了它们各自的贡献。氮，并且在较小程度上 P 添加物提高了碳利用效率（CUE，NPP：GPP）和 C 向 ANPP 的分配，而牺牲了 TBCF。GPP 分配给 APR 的部分对 N 或 P 添加物不变。在低 N 低 P 添加处理中（61%），土壤呼吸（FS）与 TBCF 的比值明显大于单一或组合 N 和 P 添加处理（49%）。生长最慢的无性系将 GPP 的一小部分（29%）分配给 ANPP，而生长较快的无性系之一（33%）则分配了更多的 GPP。这项研究深入了解了 N 和 P 如何调节单个植物的 C 通量和分配。我们的结果有助于解释地上生长速率的无性系变异，并表明，与 P 供应相比，添加 N 会带来更大的 CUE 增益和对 ANPP 的分配。
