State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, Haidian District, Beijing 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Ecosystem Carbon Source and Sink, China Meteorological Administration (ECSS-CMA), School of Applied Meteorology, Nanjing University of Information Science & Technology, 219 Ningliu Road, Nanjing 210044, China.
Sci Total Environ. 2023 Jun 1;875:162721. doi: 10.1016/j.scitotenv.2023.162721. Epub 2023 Mar 9.
Increasing ozone (O) and nitrogen (N) addition may have contradictory effects on plant photosynthesis and growth. However, it remains unclear whether these effects on aboveground parts further change the root resource management strategy and the relationships of fine root respiration and biomass with other physiological traits. In this study, an open-top chamber experiment was conducted to investigate the effects of O alone and in combination with nitrogen (N) addition on root production and fine root respiration of poplar clone 107 (Populus × euramericana cv. '74/76'). Saplings were grown with (100 kg ha year) or without (+0 kg ha year) N addition under two O regimes (non-filtered ambient air or non-filtered ambient air + 60 ppb of O). After about two to three months of treatment, elevated O significantly decreased fine root biomass and starch content but increased fine root respiration, which occurred in tandem with inhibited leaf light-saturated photosynthetic rate (A). Nitrogen addition did not change fine root respiration or biomass, neither did it alter the effect of elevated O on the fine root traits. However, N addition weakened the relationships of fine root respiration and biomass with A, fine root starch and N concentrations. No significant relationships of fine root biomass and respiration with soil mineralized N were observed under elevated O or N addition. These results imply that changed relationships of plant fine root traits under global changes should be considered into earth system process models to project more accurately future carbon cycle.
臭氧 (O) 和氮 (N) 增加可能对植物光合作用和生长产生相反的影响。然而，目前尚不清楚这些对地上部分的影响是否会进一步改变根系资源管理策略，以及细根呼吸和生物量与其他生理特性的关系。本研究采用开顶式气室实验，研究了 O 单独和与氮 (N) 加合对杨树无性系 107（Populus × euramericana cv. '74/76'）根系生产和细根呼吸的影响。在两种 O 浓度（未过滤的环境空气或未过滤的环境空气+60 ppb O）下，用或不用（+0 kg ha 年）N 处理幼苗。处理约两到三个月后，高 O 显著降低了细根生物量和淀粉含量，但增加了细根呼吸，这与抑制叶片光饱和光合作用速率 (A) 同时发生。N 添加并未改变细根呼吸或生物量，也未改变高 O 对细根特性的影响。然而，N 添加减弱了细根呼吸和生物量与 A、细根淀粉和 N 浓度的关系。在高 O 或 N 添加下，细根生物量和呼吸与土壤矿化 N 之间没有显著关系。这些结果表明，在全球变化下，植物细根特性的变化关系应该被考虑到地球系统过程模型中，以更准确地预测未来的碳循环。
