Photosynthesis occurs mainly in plant leaves and is a fundamental process in the global carbon cycle and in crop production. The exploitation of natural genetic variation in leaf photosynthetic capacity is a promising strategy to meet the increasing demand for crops. The present study reports the newly developed photosynthesis measurement system ‘MIC-100,’ with a higher throughput for measuring instantaneous photosynthetic rate in the field. MIC-100 is established based on the closed system and directly detects the CO₂ absorption in the leaf chamber. The reproducibility, accuracy, and measurement throughput of MIC-100 were tested using soybean (Glycine max L. (Merr.)) and rice (Oryza sativa L.) grown under field conditions. In most cases, the coefficient of variance (CV) for repeated-measurements of the same leaf was less than 0.1. The photosynthetic rates measured with the MIC-100 model showed a significant correlation (R² = 0.93–0.95) with rates measured by a widely used gas-exchange system. The measurement throughput of the MIC-100 is significantly greater than that of conventional open gas-exchange systems under field conditions. Although MIC-100 solely detects the instantaneous photosynthetic rate under a given environment, this study demonstrated that the MIC-100 enables the rough evaluation of leaf photosynthesis within the large-scale plant populations grown in the field.

光合作用主要发生在植物叶子中，是全球碳循环和作物生产的基本过程。利用叶片光合能力的自然遗传变异是满足作物日益增长的需求的一种有前景的策略。本研究报告了新开发的光合作用测量系统“MIC-100”，具有更高的通量，可在现场测量瞬时光合速率。 MIC-100是基于封闭系统建立的，直接检测叶室内的CO ₂吸收量。使用在田间条件下生长的大豆 ( Glycine max L. (Merr.)) 和水稻 ( Oryza sativa L.) 测试了 MIC-100 的再现性、准确性和测量通量。在大多数情况下，同一片叶子重复测量的方差系数 (CV) 小于 0.1。使用 MIC-100 模型测量的光合速率与广泛使用的气体交换系统测量的光合速率存在显着相关性 (R ² = 0.93–0.95)。在现场条件下，MIC-100 的测量吞吐量明显高于传统的开放式气体交换系统。虽然 MIC-100 仅检测给定环境下的瞬时光合速率，但本研究表明 MIC-100 能够粗略评估田间种植的大规模植物群体的叶片光合作用。