| 夏季遮光对连香树幼苗形态、光合作用及叶肉细胞超微结构的影响 |
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| 引用本文： | 李冬林,金雅琴,崔梦凡,黄琳曦,裴文慧.夏季遮光对连香树幼苗形态、光合作用及叶肉细胞超微结构的影响[J].浙江农林大学学报,2020,37(3):496-505. |
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| 作者姓名： | 李冬林 金雅琴 崔梦凡 黄琳曦 裴文慧 |
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| 作者单位： | 1.江苏省林业科学研究院，江苏 南京 2111532.金陵科技学院 园艺学院，江苏 南京 210038 |
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| 基金项目： | 江苏省重点研发计划(现代农业)项目(BE2017387) |
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| 摘 要： | 目的 光照是影响植物生长发育最重要的生态因子之一，分析遮光处理对连香树Cercidiphyllum japonicum幼苗生长及生理功能的影响，进而为其种苗繁育和拯救保护提供科学依据。 方法 通过人工遮光设置了全光照(L0)、透光率55% (L1)、透光率25% (L2)、透光率10% (L3) 4种光环境，应用LI-6400光合仪测定了不同光照条件下连香树幼苗的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、胞间二氧化碳摩尔分数(Ci)的日变化，并通过野外取样和透射电镜技术观察了遮光条件下幼苗的生长形态及叶肉细胞超微结构的变化。 结果 ①遮光影响叶片含水量及叶片形态。随着遮光强度的加大，叶片含水量、单叶面积增加，比叶重减小，比叶面积增大，并与对照相比呈现显著差异(P＜0.05)。②遮光对幼苗的光合作用产生了显著影响。全光和L1处理下Pn的变化曲线相似，均呈现不对称的“几”字形变化，未出现“午休”现象，14:00出现峰值，L2和L3处理的Pn变化相对缓和，峰值出现在12:00；Gs呈现与Pn类似的变化，而Ci则呈基本一致的凹形变化。Pn、Gs和Tr的日均值从大到小依次为L0、L1、L2、L3，Ci则呈现相反的序列变化。③ 遮光条件下，叶片叶绿素和类胡萝卜素质量分数均有一定程度增加，且随着遮光强度的加大其质量分数递增，提高了叶片的捕光能力。④全光下，叶肉组织中细胞轮廓可鉴，叶绿体数量少，紧靠细胞壁平行分布，细胞中央形成大的空腔，类囊体排列均匀，淀粉粒和嗜锇颗粒较少；遮光条件下细胞内叶绿体数量有所增加，在整个细胞中占有比例显著增大，叶绿体外形逐渐变为圆球形或椭圆形，淀粉粒数量较多，类囊体片层厚度加大，提高了弱光下的光合效率。⑤强度遮光条件(L2和L3)下，连香树苗高(H)和基径(D)依次递减，生物量模型D2H显著下降，幼苗正常的生长发育变缓；但轻度遮光(L1)与对照相比幼苗的生长指标未出现显著差异。 结论 连香树对遮光具有一定的忍耐性和可塑性，轻度遮光未对幼苗的生长带来抑制性影响；轻度遮光有利于改善林内微环境，但有效辐射光强应达自然光强的55%以上。图3表4参29
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| 关 键 词： | 植物学 连香树 遮光 光合生理 超微结构 |
| 收稿时间： | 2019-06-17 |
Growth,photosynthesis and ultrastructure of mesophyll cells for Cercidiphyllum japonicum seedlings with shading in summer |
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| LI Donglin,JIN Yaqin,CUI Mengfan,HUANG Linxi,PEI Wenhui.Growth,photosynthesis and ultrastructure of mesophyll cells for Cercidiphyllum japonicum seedlings with shading in summer[J].Journal of Zhejiang A&F University,2020,37(3):496-505. |
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| Authors: | LI Donglin JIN Yaqin CUI Mengfan HUANG Linxi PEI Wenhui |
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| Affiliation: | 1.Forestry Academy of Jiangsu, Nanjing 211153, Jiangsu, China2.Department of Horticulture, Jinling Institute of Technology, Nanjing 210038, Jiangsu, China |
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| Abstract: | Objective To provide a scientific basis for seedling breeding and population protection, the effects of shading treatment on the growth and physiological functions of Cercidiphyllum japonicum seedlings were analyzed. Method With single factor random block design was adopted, using a LI-6400 portable photosynthetic system, a series of shading experiments were conducted on C. japonicum seedlings to study the effects of light on physiological characteristics, diurnal variation of net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and intercellular CO2 concentration (Ci) with seedlings being measured in summer under four light treatments: full light (L0), 55% transmittance (L1), 25% transmittance (L2), and 10% transmittance (L3). At the same time, changes in growth, in morphological indexes, and in the ultrastructure of leaf mesophyll cells were observed by sampling and transmission electron microscope technique. Result (1) Shading affected the leaf water content (LWC) and morphology compared to the control; with an increase in shading intensity, LWC increased (P＜0.05), single leaf area (SLA) increased (P＜0.05) too, both single leaf dry weight (SLWd) and lamina mass per unit area (LMA) decreased (P＜0.05), and lamina area per unit mass (LAM) increased (P＜0.05). (2) Shading had a strong effect on photosynthesis of seedlings. The “noon break” did not appear during the course of the day. The peak value appeared at 14:00, and other treatments were relatively mild with the peak value appearing at 12:00. The variation curve for Gs was similar to Pn, and Ci basically showed a concave change. The daily average for Pn, Gs, and Tr were L0＞L1＞L2＞L3, but the order of Ci was reversed. (3) Chlorophyll and carotenoid content in leaves increased significantly with shading condition (P＜0.05), and both chlorophyll and carotenoid content increased progressively with an increase of shading intensity (P＜0.05). Long-term shading improved the light capture ability of leaves. (4) With full light: the outline of cells in the mesophyll tissue could be identified, the number of chloroplasts was small, the arrangement of chloroplasts was close to parallel to the cell wall, there was a large cavity in the center of the cells, the arrangement of thylakoid body was uniform, and the starch granules and osmium granules were few. With shading, the number of chloroplasts increased, the proportion of chloroplasts in the whole cell increased, the shape of chloroplasts gradually became spherical or oval, the number of starch grains increased, and the thickness of thylakoid lamellar was so. (5) For intensity shading L2 and L3, height (H) and basal diameter (D) decreased (P＜0.05), the biomass model D2H decreased significantly (P＜0.05), and normal growth and development of seedlings affected. However, there were no significant differences between growth indexes of seedlings for L1 (mild shade) compared to L0 (P＞0.05). Thus, intensity shading has a great effect on the growth of seedlings. Conclusion The mild shading possibly beneficial for the growth environment of forests and having no obvious inhibitory effect on seedling growth, but the effective radiation intensity should be more than 55% of natural light intensity. Ch, 3 fig. 4 tab. 29 ref.] |
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