Seasonal change in response of stomatal conductance to vapor pressure deficit and three phytohormones in three tree species

ABSTRACT

Stomatal behavior under global climate change is a central topic of plant ecophysiological research. Vapor pressure deficit (VPD) and phytohormones can affect stomata of leaves which can affect gas exchange characteristics of plant. The role of VPD in regulating leaf gas exchange of three tree species was investigated in Jinan, China. Experiments were performed in June, August, and October. Levels of three phytohormones (GA₃, IAA, ABA) in the leaves of the three trees were determined by high-performance liquid chromatography in three seasons. The responses of stomatal conductance (g_s) to an increasing VPD in the leaves of the three trees had peak curves under different seasons, which differed from the prevailing response pattern of g_s to VPD in most literature. The peak curve could be fitted with a Log-Normal Model (R² = 0.838–0.995). The VPD/RH values of the corresponding maximum of g_s (g_s-max-VPD/RH) could be calculated by fitted models. The g_s-max-RH could be affected by environmental conditions, because of positive correlation between g_s-max-RH and the mean monthly temperature in 2010 (R² > 0.81). Two typical stomatal models (the Leuning model and the optimal stomatal behavior model) were used to estimate g_s values, but they poorly predicted g_s in the three trees. The concentration of ABA was positively correlated to sensitivity in response of stomatal conductance to VPD in the leaves of the tree species during the different seasons.

KEYWORDS:

• Abscisic acid
• relative humidity
• stomatal conductance
• stomatal model
• vapor pressure deficit

Acknowledgments

The authors thank Dr. Pamela Holt very much for improving the English-writing of the manuscript.

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Additional information

Funding

This work was supported partly by the National Natural Science Foundation of China [30270146] and Young Teachers’ Scientific Research Fund of Shandong Agriculture and Engineering University [QNKJY201803].