不同遮阴处理对七叶一枝花生长 光合特性及品质的影响

目的 七叶一枝花是典型的阴生植物，研究不同遮阴条件对七叶一枝花叶片光合作用、生长和代谢产物含量的影响。方法 在85%和95%遮阴条件下，采用紫外-可见分光光度法测定七叶一枝花叶片的光合色素含量，运用便携式光合作用测定仪测定叶片净光合速率（P_n）、胞间二氧化碳浓度（C_i）、蒸腾速率（T_r）、气孔导度（G_s）并拟合光响应曲线，测定植株的生长指标并利用超高效液相色谱-紫外法（UPLC-UV）与高效液相色谱-蒸发光散射检测法（HPLC-ELSD）测定不同部位皂苷类及糖类成分含量。结果 95%遮阴条件下叶绿素含量与植株生长指标均优于85%遮阴；95%遮阴条件下叶片的日光合速率低于85%遮阴，但C_i、T_r和G_s的光响应差异无统计学意义；不同遮阴条件对重楼皂苷Ⅰ、重楼皂苷Ⅱ、重楼皂苷H、薯蓣皂苷、纤细薯蓣皂苷含量有极显著影响，且往年生根茎和须根中重楼皂苷Ⅰ、重楼皂苷Ⅱ、重楼皂苷Ⅶ总量在2种遮阴条件下差异有统计学意义（P<0.01），85%遮阴较高；不同遮阴条件对根部的蔗糖含量影响较大，95%遮阴处理蔗糖含量较高。七叶一枝花移栽到北京后极喜阴，在95%遮阴下植株农艺性状得到改善。结论 研究结果为开展优化遮阴度和遮阴时间以平衡植物生长、增加活性代谢产物的积累研究提供参考。

Effects of Shading on Growth, Photosynthesis, and Quality of Paris polyphylla var. chinensis

Objective Paris polyphylla Smith var. chinensis (Franch.) Hara (PPC) is a typical shady plant, its growth, development, and metabolite accumulation are benefit from proper shading.Methods A field experiment containing two shading treatments was carried out to investigate the effects of shading intensity on the photosynthesis, growth, and metabolite content of PPC. The photosynthetic pigment content and photosynthetic characteristics including P_n (net photosynthetic rate), C_i (intercellular carbon dioxide concentration), T_r (transpiration rate), and G_s (stomatal conductance) were measured during the growth stage of PPC in summer. UPLC-UV and HPLC-ELSD were respectively employed to determine the contents of eight saponins and four sugars in different PPC tissues.Results The results showed that PPC plants grown under 95% shading condition had higher chlorophyll content and larger aboveground growth indicators than the plants under 85% shading condition. The PPC plants under two shading conditions showed no significant differences in C_i, T_r, or G_s. However, 85%-shaded leaves had a higher daily photosynthetic rate than 95%-shaded leaves. Overall, the contents of saponins, especially the abundant saponins, were higher in old and new rhizomes, fibrous roots, and leaves under 85% shading condition than under 95% shading condition. Sugar content was less affected by shading intensity, and only sucrose content showed a small difference between two shading treatments.Conclusion These results provide a theoretical basis to optimize shading intensity and duration to balance plant growth and increase accumulation of active metabolites in medicinal plants.