Short-term responses of plant dark respiration to carbon dioxide concentration ([CO2]) in the range anticipated in the atmosphere with global change remain controversial, primarily because it is difficult to convincingly eliminate the many possible sources of experimental error in measurements of carbon dioxide or oxygen exchange rates. Plant dark respiration is a major component of the carbon balance of many ecosystems. In seedlings without senescent tissue, the rate of loss of dry mass during darkness indicates the rate of respiration. This method of measuring respiration was used to test for [CO2] effects on respiration in seedlings of three species with relatively large seeds. The time it took respiration to exhaust substrates and cause seedling death in darkness was used as an indicator of respiration rate in four other species with smaller seeds. The third method was measuring rates of CO2 exchange in excised petioles sealed in a cuvette submerged in water to prevent leaks. Petioles were utilized as the plant tissue type with the most reliable rates of respiration, for excised tissue. The rate of loss of dry mass in the dark decreased with increasing [CO2] in the range of 200–800 μmol mol−1 in all three large-seeded species. The seedling survival time in the dark increased with [CO2] in the same concentration range in all four of the smaller-seeded species. Respiration rates of excised petioles of several species also decreased over this [CO2] range. The data provide new evidence that the rate of dark respiration in plant tissue often decreases with increasing [CO2] in the 200–800 μmol mol−1 range.

中文翻译：

---

三种新方法表明二氧化碳浓度在与全球变化相关的范围内影响植物呼吸

植物暗呼吸对大气中二氧化碳浓度（[CO2]）在全球变化的预期范围内的短期响应仍然存在争议，主要是因为难以令人信服地消除二氧化碳测量中许多可能的实验误差来源或氧气交换率。植物暗呼吸是许多生态系统碳平衡的主要组成部分。在没有衰老组织的幼苗中，黑暗期间干物质的损失速率表明呼吸速率。这种测量呼吸的方法用于测试 [CO2] 对种子相对较大的三个物种幼苗呼吸的影响。呼吸耗尽底物并导致幼苗在黑暗中死亡的时间被用作其他四个种子较小的物种的呼吸速率指标。第三种方法是测量切下叶柄中的二氧化碳交换率，该叶柄密封在浸没在水中的比色皿中，以防止泄漏。叶柄被用作具有最可靠呼吸速率的植物组织类型，用于切除组织。在所有三种大种子物种中，在 200-800 μmol mol-1 范围内，黑暗中干质量的损失率随着 [CO2] 的增加而降低。在所有四个较小种子物种中，在相同浓度范围内的 [CO2] 黑暗中的幼苗存活时间增加。在这个 [CO2] 范围内，几个物种的离体叶柄的呼吸速率也降低了。