Response of Leaf Stomatal Characteristics of Three Species of Juniperus to Natural Light Intensity

Abstract

【Objective】Light-induced stomatal opening and closing is an important factor regulating CO2 intake and transpiration in plants. The study of plant stomatal characteristics under different light environments is helpful to understand the mechanism of plant adaptation to the environment.【Method】Taking three species of Juniperus plants with heteromorphic leaves widely cultivated in northern China as research objects, the stomatal characteristics were observed and parameters were measured by using NaClO method, and the stomatal characteristics and their correlation under short-term light change (diurnal change) and long-term light difference (shady and sunny sides of the canopy) in the same habitat were investigated.【Result】The leaves of three species of Juniperus had two leaf shapes. The stomata of scale leaves were distributed on the adaxial side and the abaxial side at the junction of two scale-like leaves, and the stomata of thorn leaves were only distributed on the adaxial side with two stomatal bands. Under diurnal changes, the width of guard cells in leaves of the three species of Juniperus at noon decreased significantly by 0.06%, 0.09% and 0.09% compared with that in the morning, and the stomatal opening increased significantly by 27.6%, 24.3% and 24.3%, and they were negatively correlated, however, there was no significant difference in guard cell length and stomatal density between morning and noon, indicating that the three species regulated stomatal aperture to adapt to short-term light changes mainly by guarding the contraction of cell width.【Conclusion】There were significant differences in guard cell length and width, stomatal density and stomatal aperture between the sunny leaves and the shady leaves of the canopy of the three species, and the first three parameters were significantly correlated with stomatal aperture, indicating that the three species changed stomatal aperture by regulating guard cells in length and width and stomatal density to adapt to the long-term light difference. Stomatal characteristics can better reflect the difference of plant adaptability to long-term and short-term light.

Keywords

• juniperus
• stomata
• light intensity
• shady and sunny sides of the canopy
• diurnal change