5种蕨类植物的羽片与叶柄水力协调研究

Hydraulic Coordination Between Pinnae and Petioles in Five Fern Species

摘要:

为探究蕨类植物的羽片-叶柄水力协调机制，对5种蕨类植物[毛蕨(Cyclosorus interruptus)、双盖蕨(Diplazium donianum)、肾蕨(Nephrolepis cordifolia)、松叶蕨(Psilotum nudum)、蜈蚣凤尾蕨(Pteris vittata)]羽片的压力-容积曲线进行测定，并分析羽片和叶柄的形态结构及其水力功能之间的关联性。结果表明，蜈蚣凤尾蕨的羽片和叶柄的水力效率(羽片理论导水率K_leaf和叶柄理论导水率K_th)和羽片水力安全性(膨压丧失点的水势Ψ_tlp)均高于其他物种。双盖蕨的羽片表现出最高的储水能力[绝对水容(C_T)和饱和含水量(SWC)]，但其安全性最低。双盖蕨有最密集且较小的气孔及最高的最小叶表导度(g_min)，松叶蕨则具有最稀疏且较大的气孔，蜈蚣凤尾蕨的最大理论气孔导度(g_s,max)高于其他物种。蕨类植物叶柄与羽片的供耗水存在协调关系。叶柄供水功能与气孔性状显著相关，较高的K_th伴随较小且密集的气孔分布和较大的g_s,max。此外，g_s,max与叶柄木质部面积呈显著正相关(P<0.05)，而g_min与SWC呈显著正相关(P<0.05)。羽片的水力效率与水力安全性存在协调关系(P<0.01)，即具有较高K_leaf的羽片具备更负的Ψ_tlp。这揭示了羽片与叶柄的水力协调机制，表明蕨类植物通过结构-功能协调优化实现水分运输效率与蒸腾需求间的动态平衡，这一适应性策略可能增强其对环境的适应能力。

Abstract:

To explore the hydraulic coordination mechanism between leaflets and petioles of ferns, the pressure-volume curves of leaflets of five fern species (Cyclosorus interruptus, Diplazium donianum, Nephrolepis cordifolia, Psilotum nudum and Pteris vittata) were measured, and the correlations between the morphological structures of leaflets and petioles and their hydraulic functions were analyzed. The results showed that the hydraulic efficiency [theoretical water conductivity of leaflets (K_leaf) and theoretical water conductivity of petioles (K_th)] and the hydraulic safety [water potential at the loss of turgor pressure (Ψ_tlp)] of Pteris vittata were higher than those of other species. The pinnae of D. donianum exhibited the highest water storage capacity [absolute water capacity (C_T) and saturated water content (SWC)], but its safety was the lowest. Diplazium donianum had the most dense and smaller stomata and the highest minimum leaf surface conductance (g_min), while Psilotum nudum had the most sparse and larger stomata. The maximum theoretical stomatal conductance (g_s,max) of Pteris vittata was higher than that of other species. The supply and consumption of water by petioles and leaflets of ferns were coordinated. The water supply function of petioles was significantly correlated with the stomatal traits. Higher K_th was accompanied by smaller and denser stomatal distribution and larger g_s,max. In addition, g_s,max was significantly positively correlated with the area of xylem in petiole) (P<0.05), and g_min is significantly positively correlated with SWC (P<0.05). The hydraulic efficiency was coordinated with hydraulic safety in pinnae (P<0.01), meaning that pinnae with higher K_leaf have more negative Ψ_tlp. This revealed the hydraulic coordination mechanism between pinnae and petioles of ferns, indicating that ferns achieve a dynamic balance between water transport efficiency and transpiration demand through structural-functional coordination. This adaptive strategy might enhance their adaptability to the environment.