Lipp Cynthia C, Andersen Christian P
Dynamac Corporation 200 SW 35th Street, Corvallis, OR 97333 USA.
Western Ecology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR, 97333 USA.
New Phytol. 2003 Dec;160(3):523-531. doi: 10.1046/j.1469-8137.2003.00914.x.
• Respiration of intact ponderosa pine (Pinus ponderosa) fine roots (< 2.5 mm) was measured to determine the role of recently fixed carbohydrate in maintaining root metabolism of growing white (WR) and recently suberized brown roots (BR). • The CO efflux and O uptake of individual roots were followed continuously over 24 h after carbohydrate supply was altered by exposing shoots to light/dark treatments and by root excision. • In situ respiration of individual WR and BR averaged 86.0 ± 2.6 and 21.1 ± 1.5 mol CO g h , respectively. Growth respiration was estimated to be approximately two-thirds the rate of WR respiration. Attached WR and BR respiration did not decline significantly over 24 h under continuous light. The WR respiration significantly decreased during a dark period. All roots maintained relatively constant respiration rates for at least 6 h after excision. Respiratory quotient (RQ; CO : O ) was not different between attached (0.84 ± 0.014) and detached (0.85 ± 0.017) roots. CO environment of the cuvette did not influence WR or BR respiration. • The WR appear to be more sensitive to supply of current photosynthate than BR. Shoot light environment needs to be considered when measuring root and soil CO efflux.
• 测量了完整的黄松（Pinus ponderosa）细根（<2.5毫米）的呼吸作用，以确定新固定的碳水化合物在维持生长中的白根（WR）和近期栓质化的棕根（BR）的根系代谢中的作用。
• 通过对枝条进行光照/黑暗处理以及切除根系来改变碳水化合物供应后，连续24小时跟踪单个根系的CO₂流出量和O₂吸收量。
• 单个WR和BR的原位呼吸平均速率分别为86.0±2.6和21.1±1.5 μmol CO₂ g⁻¹ h⁻¹。生长呼吸估计约为WR呼吸速率的三分之二。在持续光照下，附着的WR和BR呼吸在24小时内没有显著下降。在黑暗期，WR呼吸显著下降。所有根系在切除后至少6小时内保持相对恒定的呼吸速率。呼吸商（RQ；CO₂:O₂）在附着根系（0.84±0.014）和分离根系（0.85±0.017）之间没有差异。比色皿中的CO₂环境不影响WR或BR呼吸。
• WR似乎比BR对当前光合产物的供应更敏感。在测量根系和土壤CO₂流出量时需要考虑枝条的光照环境。
