Department of Systematic and Environmental Botany, The Adam Mickiewicz University, Poznań, Poland.
The Botanical Garden, The Adam Mickiewicz University, Poznań, Poland.
PLoS One. 2023 Sep 8;18(9):e0291122. doi: 10.1371/journal.pone.0291122. eCollection 2023.
Welwitschia mirabilis Hook.f. (Welwitschiaceae, Gnetales) is a gymnosperm plant unique in its habit with an isolated taxonomic position. This species is dioecious, but no studies of its photosynthetic activity were conducted with examination of differences among male and female plants. To fill this gap, the day and night photosynthetic activity of male and female specimens of Welwitschia mirabilis cultivated in the botanical garden was studied in controlled conditions. Photosynthetic activity was studied using net photosynthetic rate (PN), stomatal conductance (gs) and intercellular CO2 concentration (Ci) parameters. Additionally, a normalized difference vegetation index (NDVI) was used to assess the condition among male and female plants in full sunlight. The studied Welwitschia plants revealed variability in photosynthetic activity both during the day and the night. The photosynthetic activity was low in the morning hours and higher in the afternoon. There is a difference in the photosynthetic activity during the night between sexes, being higher in female specimens. Stomatal density was evaluated separately for adaxial and abaxial leaf surfaces. Statistically significant differences in the stomatal density on abaxial and adaxial leaf surfaces were observed in both sexes, especially distinctive in female specimens. NDVI has revealed that there were weak differences between male and female plants.
奇异南洋杉（南洋杉科，买麻藤目）是一种以其独特的习性而独特的裸子植物，具有孤立的分类地位。该物种是雌雄异株的，但没有对雄性和雌性植物之间的差异进行检查的光合作用活性研究。为了填补这一空白，在受控条件下研究了在植物园中种植的奇异南洋杉的雄性和雌性标本的白天和夜间光合作用活性。使用净光合速率 (PN)、气孔导度 (gs) 和胞间 CO2 浓度 (Ci) 参数来研究光合作用活性。此外，归一化差异植被指数 (NDVI) 用于评估全日照下雄性和雌性植物的状况。所研究的奇异南洋杉植物在白天和夜间的光合作用活性均表现出可变性。清晨的光合作用活性较低，下午较高。在夜间，雌雄之间的光合作用活性存在差异，雌性标本的光合作用活性较高。分别评估了叶正面和叶背面的气孔密度。在两性中均观察到叶背面和叶正面的气孔密度存在统计学上的显著差异，尤其是在雌性标本中更为明显。NDVI 表明雄性和雌性植物之间存在微弱差异。
