AUTHOR=Lv Yuping , Gu Linhui , Man Runze , Liu Xiaoyin , Xu Junzeng 

TITLE=Response of stomatal conductance, transpiration, and photosynthesis to light and CO2 for rice leaves with different appearance days

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1397948

DOI=10.3389/fpls.2024.1397948

ISSN=1664-462X

ABSTRACT=<p>To investigate the dynamics of stomata, transpiration, and photosynthesis under varying light intensities and CO<sub>2</sub> conditions during leaf development, the light response and CO<sub>2</sub> response of stomatal conductance (<italic>g</italic><sub>sw</sub>), transpiration rate (<italic>T</italic><sub>r</sub>), and net photosynthetic rate (<italic>P</italic><sub>n</sub>) were observed for rice leaves at different days after leaf emergence (DAE). The results showed that (1) as photosynthetically active radiation (PAR) increased, leaf <italic>g</italic><sub>sw</sub>, <italic>T</italic><sub>r</sub>, and <italic>P</italic><sub>n</sub> initially increased rapidly and linearly, followed by a more gradual rise to maximum values, and then either stabilized or showed a declining trend. The maximum <italic>g</italic><sub>sw</sub>, <italic>T</italic><sub>r</sub>, and <italic>P</italic><sub>n</sub> were smaller and occurred earlier for old leaves than for young leaves. The <italic>g</italic><sub>sw</sub>, <italic>T</italic><sub>r</sub>, and <italic>P</italic><sub>n</sub> all exhibited a linear decreasing trend with increasing DAE, and the rate of decrease slowed down with the reduction in PAR; (2) as the CO<sub>2</sub> concentration (<italic>C</italic><sub>a</sub>) increased, <italic>g</italic><sub>sw</sub> and <italic>T</italic><sub>r</sub> decreased gradually to a stable minimum value, while <italic>P</italic><sub>n</sub> increased linearly and slowly up to the maximum and then kept stable or decreased. The <italic>g</italic><sub>sw</sub>, <italic>T</italic><sub>r</sub>, and <italic>P</italic><sub>n</sub> values initially kept high and then decreased with the increase of DAE. These results contribute to understanding the dynamics in <italic>g</italic><sub>sw</sub>, <italic>T</italic><sub>r</sub>, and <italic>P</italic><sub>n</sub> during rice leaf growth and their response to varied light and CO<sub>2</sub> concentration conditions and provide mechanistic support to estimate dynamic evapotranspiration and net ecosystem productivity at field-scale and a larger scale in paddy field ecosystems through the upscaling of leaf-level stomatal conductance, transpiration, and photosynthesis.</p>