| 摘要: |
| 【目的】了解不同光照条件下桢楠（Phoebe zhennan）幼苗的生长状况和光合生理特性，探讨有利于桢楠幼苗生长发育的最佳光照条件。【方法】采用遮阴方式模拟不同光照强度（即全光照、遮阴率50%、75%和87.5% 4个水平），分析桢楠幼苗形态生长、光合色素含量、叶绿素荧光参数等光合特性的响应规律。【结果】（1）随遮阴程度的增强，桢楠幼苗的株高生长量呈先升后降的趋势，地径生长量逐渐减小；（2）遮阴造成桢楠幼苗叶绿素总量、类胡萝卜素含量增加，叶绿素a/b值降低；净光合速率Pn、蒸腾速率Tr、气孔导度Gs、表观量子效率AQY、光饱和点LSP、最大净光合速率Pn max均随遮阴程度的增强而先升后降，光补偿点LCP、暗呼吸速率Rd、光呼吸速率Rp均逐渐降低；（3）遮阴下PSⅡ潜在活性Fv/F0、PSⅡ最大光化学量子产量Fv/Fm、PSⅡ有效光化学量子产量Fv′/Fm′、PSⅡ实际光化学量子产量ΦPSⅡ、光化学淬灭系数qP、光化学耗散比例P均有不同程度提升，非光化学淬灭系数NPQ、天线热耗散比例D下降。轻度遮阴能够提高桢楠幼苗光合性能，促进其生长发育，而重度遮阴下虽然其光捕获能力、光能利用效率较高，但光能的严重缺乏限制了其生长发育。【结论】桢楠幼苗对弱光环境的适应性较强，其最适遮阴率为50%。 |
| 关键词: 桢楠 遮阴 气体交换 光合响应 光能分配 |
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| 基金项目:四川省“十三五”农作物育种攻关项目(2016NZ0098-10);四川省教育厅重点项目(13ZA0246) |
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| Effects of shading on growth and photosynthetic characteristics of Phoebe zhennan seedlings |
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DAI Dachuan,HU Hongling,CHEN Hong,et al
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| Abstract: |
| 【Objective】This study aimed to understand the growth and photosynthetic characteristics of Phoebe zhennan seedlings under different light conditions and explored the best light conditions for the growth and development of P. zhennan seedlings.【Method】Shading method was used to simulate different light intensities (full light,shading rate 50%,75%,and 87.5%) and morphological growth,chlorophyll content,chlorophyll fluorescence parameters and photosynthetic characteristics of seedlings were analyzed.【Result】(1) With the increase of shading degree,the increment of plant height showed a trend of rising at the beginning followed by falling while the increment of ground diameter decreased gradually.(2) Shading resulted in the increase of total contents of chlorophyll and carotenoid and the decrease of chlorophyll a/b ratio.Net photosynthetic rate (Pn),transpiration rate (Tr),stomatal conductance (Gs),apparent quantum efficiency (AQY),light saturation point (LSP) and maximum net photosynthetic rate (Pn max) increased first and then decreased with the increase of shading degree,while light compensation point (LCP),dark respiration rate (Rd) and light respiration rate (Rp) decreased.(3) Under shading, potential activity of PSⅡ (Fv/F0),maximal quantum yield of PSⅡ (Fv/Fm),photochemical efficiency of PSⅡ (Fv′/Fm′),actual photochemical efficiency of PSⅡ (ΦPSⅡ),photochemical quenching coefficient (qP) and fraction of excitation energy utilized for photochemistry (P) all increased,while non photochemical quenching coefficient (NPQ) and fraction of absorbed light dissipated thermally (D) decreased.Moderate shading improved the photosynthetic performance and promote the growth and development.Under excessive shading,although the light capture ability and light energy utilization rate were higher,the growth and development were inhibited by lack of light.【Conclusion】The seedlings of P. zhennan showed strong adaptability to weak light environments and the optimum shading rate was 50%. |
| Key words: Phoebe zhennan shading gas exchange photosynthetic response allocation of absorbed light |
