Quantifying photosynthetic O₂ evolution in woody species: a comparative study using portable gas pressure sensing

Аннотация

Photosynthesis is a critical biological process that sustains ecosystems by producing organic substances and releasing oxygen (O₂). Quantifying this process is essential for ecological and physiological studies. In this study, we evaluated the use of a modern, portable Globisens Labdisc pressure sensor to measure photosynthetic O₂ evolution in a sealed, CO₂-buffered environment. The experiment focused on leaves from four woody species: Oak (Quercus robur), Elm (Ulmus spp.), Tree of Heaven (Ailanthus altissima), and Poplar (Populus spp.). We calculated the specific photosynthetic rate by normalizing the rate of pressure increase (ΔP) by leaf fresh weight and time (kPa g⁻¹ min⁻¹). Our results demonstrated significant differences in photosynthetic activity among species. The highest specific rate was recorded in Elm (Ulmus) (0.159 kPa g^-1 min^-1), followed by Oak (Quercus robur) (0.149), Poplar (Populus) (0.141), and Tree of Heaven (Ailanthus altissima) (0.119). These findings highlight the importance of correct data normalization, as analysis of total pressure change alone provided misleading rankings. We conclude that the Globisens Labdisc is an effective and accessible tool for quantitative, comparative measurements of photosynthetic O₂ release, suitable for both educational and preliminary research applications