Seasonal changes in canopy photosynthesis and respiration, and partitioning of photosynthate, in rice (Oryza sativa L.) grown under free-air CO2 enrichment
Seasonal changes in canopy photosynthesis and respiration, and partitioning of photosynthate, in rice (Oryza sativa L.) grown under free-air CO2 enrichment
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DOI：
10.1093/pcp/pci186
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发表时间：
2005-10-01
影响因子：
4.9
通讯作者：
Kobayashi, K
中科院分区：
文献类型：
--
作者：
Sasaki, H;Hara, T;Kobayashi, K
一般认为，大气CO2浓度（[CO2]）的增加会增强光合作用和生物量。水稻（Oryza sativa L.）在环境CO2 （AMB）和自由空气CO2富集（FACE）条件下生长，目标CO2浓度为AMB以上200 μ mol mol（-1）。（CO2）-C-13在不同的阶段被喂给植物，这样我们就可以检查光合作用的分配。在此基础上，测定了各阶段的冠层光合作用和呼吸作用。营养期全株C-13含量与固定C-13量之比，FACE处理与AMB处理相似。灌浆阶段，FACE处理的灌浆速率大于AMB处理。在营养阶段，FACE处理下生长的植物生物量大于AMB处理下生长的植物生物量，这是由于增加的[CO2]增强了冠层光合作用。另一方面，灌浆期CO2富集促进了光合产物向穗部的分配，FACE处理下植株的穗重更大。然而，CO2富集对穗重的增强不如营养期生物量的增强。在灌浆期，FACE处理下生长的植株不一定表现出更高的冠层光合速率。综上所述，籽粒灌浆期CO2增益优势丧失，导致营养期穗重增幅不及生物量增幅。
An increase in atmospheric CO2 concentration ( [CO2]) is generally expected to enhance photosynthesis and biomass. Rice plants (Oryza sativa L.) were grown in ambient CO2 (AMB) or free-air CO2-enrichment (FACE), in which the target [CO2] was 200 mu mol mol(-1) above AMB. (CO2)-C-13 was fed to the plants at different stages so we could examine the partitioning of photosynthates. Furthermore, canopy photosynthesis and respiration were measured at those stages. The ratio of C-13 content in the whole plant to the amount of fixed C-13 under FACE was similar to that under AMB at the vegetative stage. However, the ratio under FACE was greater than the ratio under AMB at the grain-filling stage. At the vegetative stage, plants grown under FACE had a larger biomass than those grown under AMB owing to enhancement of canopy photosynthesis by the increased [CO2]. On the other hand, at the grain-filling stage, CO2 enrichment promoted the partitioning of photosynthate to ears, and plants grown under FACE had a greater weight of ears. However, enhancement of ear weight by CO2 enrichment was not as great as that of biomass at the vegetative stage. Plants grown under FACE did not necessarily show higher canopy photosynthetic rates at the grain-filling stage. Therefore, we concluded that the ear weight did not increase as much as biomass at the vegetative stage owing to a loss of the advantage in CO2 gain during the grain-filling period.