Zhang Feng-Ping, Zhao Xiao-Di, Han Li-Jun, Li Han-Run
College of Traditional Chinese Medicine, Yunnan Key Laboratory of Dai and Yi Medicines, Yunnan University of Chinese Medicine, Kunming, Yunnan, 650500, China.
Kunming Botanical Garden, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China.
Bot Stud. 2025 Mar 24;66(1):11. doi: 10.1186/s40529-025-00457-z.
Leaf stomatal conductance is an important indicator of photosynthetic capacity. However, stomatal conductance is poorly quantified and rarely explored in the context of the leaf functional traits for epiphytes, particularly when it comes to herbaceous species with different leaf habits (deciduous vs. deciduous species). Here, we investigated leaf stomatal conductance, leaf dry mass per unit area, leaf thickness, stomatal density, abaxial epidermal cell size and pigment contents in 23 Dendrobium evergreen and deciduous species from a greenhouse. Our main objectives were to compare differences in all measured traits between evergreen and deciduous species, and to determine the relationships of leaf stomatal conductance with leaf functional traits and leaf pigments.
The results showed that the evergreen species of Dendrobium had thicker leaves and higher leaf dry mass per unit area, whereas deciduous species had higher leaf stomatal conductance and higher leaf chlorophyll contents. Leaf stomatal conductance had a negative correlation with leaf thickness, and dry mass per unit area, but a positive correlation with leaf pigment contents. There was a negative correlation between pigment contents and leaf dry mass per unit area.
The results reveal the clear differences in leaf stomatal conductance, leaf functional traits and leaf pigments between deciduous and evergreen Dendrobium species, with the form groups showing trait values indicative of less investments in structural components and of more investments in photosynthetic carbon gain. Furthermore, leaf dry mass per unit area and leaf pigments play an important role in shaping leaf stomatal conductance.
叶片气孔导度是光合能力的重要指标。然而，在附生植物的叶片功能性状背景下，气孔导度的量化较差且很少被研究，特别是对于具有不同叶习性（落叶与常绿）的草本物种。在此，我们调查了温室中23种常绿和落叶石斛的叶片气孔导度、单位面积叶干质量、叶厚度、气孔密度、叶背表皮细胞大小和色素含量。我们的主要目标是比较常绿和落叶物种之间所有测量性状的差异，并确定叶片气孔导度与叶片功能性状和叶片色素之间的关系。
结果表明，常绿石斛物种的叶片更厚，单位面积叶干质量更高，而落叶物种的叶片气孔导度更高，叶绿素含量更高。叶片气孔导度与叶厚度和单位面积干质量呈负相关，但与叶片色素含量呈正相关。色素含量与单位面积叶干质量之间呈负相关。
结果揭示了落叶和常绿石斛物种在叶片气孔导度、叶片功能性状和叶片色素方面的明显差异，形态组显示出性状值表明在结构成分上的投资较少，而在光合碳获取上的投资较多。此外，单位面积叶干质量和叶片色素在塑造叶片气孔导度方面起着重要作用。
