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作 者 ：马田, 刘肖, 李骏, 张旭东, 何红波

期 刊 ：核农学报 2014年 28卷 12期 页码：2238-2246

关键词：13C示踪；CO2浓度升高；光合C；分配；土壤-植物系统；

Keywords:13C-labelling, ElevatedCO2, PhotosyntheticC, Allocation, Soil-plantsystem,

摘 要 ：

光合碳在土壤-植物系统的分配与截获是生态系统碳循环过程研究中的重要科学问题,解决这个问题对农田生态系统未来大气CO₂浓度升高或CO₂施肥条件下的农田土壤碳截获能力评价具有重要意义。实现土壤-植物系统新老碳的区分必须依赖于同位素示踪技术。因此,研究利用¹³C标记CO₂供给春小麦生长,并在小麦不同生长阶段(拔节期、抽穗期和成熟期)测定光合C在小麦植株中的富集动态以及转运到地下部分的碳同化物变化。结果表明:CO₂浓度升高可促进植物光合作用,产生更多的碳同化产物,增加小麦各器官生物量,增幅在拔节期最为显著。CO₂浓度升高同时显著提高了光合C在小麦各器官的富集程度。在收获期,籽实中积累的光合C数量在CO₂浓度升高条件下显著高于常规浓度,表明CO₂浓度升高通过增加生物量,促进光合C的富集而提高了作物产量。随着小麦的生长,土壤中¹³C富集比例不断增加,但是在一个生长季中土壤有机碳含量并未发生显著变化,表明光合C不断向土壤转化并促进了SOC的更新。在常规CO₂浓度下,经过小麦一个生长季后共有 140mg·kg^-1的¹³C进入土壤,其中植物光合C所占比例为97.9%。在CO₂升高条件下,土壤¹³C富集比例在拔节期和抽穗期与常规CO₂处理没有显著差异,到了成熟期¹³C富集比例由-17.9‰增至3.1‰,比常规CO₂浓度处理提高了52.4%,表明更多的光合C在作物营养生长后期通过根系过程进入土壤,促进了SOC的更新。

Abstract:The accumulation and dynamic distribution of photosynthetic products in soil-plant system under elevated CO₂is an important scientific issue in the carbon cycle of ecosystems. If this issue can be clarified, it will be of great significance for evaluating of soil carbon sequestration in agricultural ecosystem under the scenario of elevated CO₂. In order to investigate the formation, accumulation and dynamic distribution of photosynthetic product in soil-plant system and its relationship with the crop growth under elevated atmospheric CO₂,¹³C-labelled CO₂was supplied continuously at two levels to spring wheat in sealed greenhouses during a grow season. The¹³C enrichment dynamics in the different organs of the wheat at different stages (i.e., jointing, heading and harvest stage) were determined and the transformation of the photosynthetic C into the belowground parts was measured simultaneously. The results show that the elevated CO₂could enhance plant photosynthesis to increase the biomass of all parts of wheat, especially at the jointing stage. In addition, the elevated CO₂ increased the enrichment of photosynthetic C in all parts in the wheat. At the harvest stage, the accumulation of photosynthetic C in the seeds suggested that elevated CO₂eventually increased the wheat yield by increasing the biomass and enhancing the accumulation of photosynthetic C. At both CO₂levels, the¹³C enrichment in the soil increased with the growth of wheat, but the content of soil organic carbon (SOC) did not change significantly in the current season, indicating the significant transformation of the photosynthetic carbon into soil constituents and thus enhancing the renewal of SOC. After a growing season of wheat, there is a total of 140mg·kg^{-1 13}C incorporate into the soil under the ambient CO₂ supply with the photosynthetic C contribution of 97.9%. At jointing and heading stages, there was no significant difference of¹³C enrichment of the soil between the two CO₂ levels. However, the value increased significantly (from -17.9‰ to 3.1‰) under the elevated CO₂,after wheat harvest, suggesting that more photosynthetic C were transferred into the soil by the process of roots and thus the renewal of SOC was enhanced significantly with the percentage up to 52.4%.

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