8种绿化树种光合特性及叶片解剖结构比较

城市绿化不仅包含了园林绿化的美化作用,还具有重要的生态功能,其生态功能是通过植物的生理活动实现的。光合能力在种间和基因型间的变化很大,这些差异通常与代谢和(或)叶片的解剖结构的性质有关。本研究选择8种哈尔滨常见树种,采用Li-6400便携式光合测定系统对叶净光合速率(P_n)、呼吸速率(R_d)、蒸腾速率(T_r)、气孔导度(G_s)、胞间CO_2浓度(C_i)等进行测定,并利用显微镜观察测定叶片厚度、表皮厚度、栅栏组织厚度、海绵组织厚度,从而探讨叶片结构对光合生理的影响。结果表明:8个树种间叶片最大光合速率、气孔导度、胞间CO_2浓度、蒸腾速率、光饱和点差异显著(P <0.05);表皮厚度、栅栏组织厚度、上表皮气孔密度和下表皮气孔密度差异显著(P <0.05)。虽然8个树种间光合能力和叶片解剖结构的差异较大,但分析发现其间也存在一定的相关性。其中,光饱和点与叶表皮厚度显著正相关(P <0.01),相关系数为0.78。胞间CO_2浓度与上表皮气孔密度显著负相关(P <0.05),相关系数为-0.65。而最大光合速率、呼吸速率、蒸腾速率和光补偿点与表皮厚度、栅栏组织厚度、海绵组织厚度、上表皮气孔密度和下表皮气孔密度相关均不显著(P> 0.05)。胞间CO_2浓度与表皮厚度、栅栏组织厚度、海绵组织厚度和下表皮气孔密度相关均不显著(P> 0.05)。光饱和点与栅栏组织厚度、海绵组织厚度、上表皮气孔密度和下表皮气孔密度相关均不显著(P> 0.05)。虽然对叶片结构对生理过程的影响的机理还需要进一步研究,但是我们认为叶片解剖结构的研究可以更好地理解生理指标的变化。

Photosynthetic Characteristics and Leaf Anatomical Structure of Eight Tree Species

Urban greening not only includes the beautification of landscaping, but also has important ecological functions, and its ecological function is realized through the physiological activities of plants. Photosynthetic capacity often varies appreciably among species and genotypes. Such variations are usually related to basic differences in metabolism and/or leaf anatomy. The experiment was conducted to study the influence of leaf anatomical structure on photosynthetic characteristics in eight tree species in Harbin. Photosynthetic rate(P_n), respiratory rate(R_d), transpiration rate(T_r), stomatal conductance(G_s) and intercellular CO₂ concentration(C_i) were measured by a portable photosynthesis system(Model Li-Cor 6400). The leaf anatomical structure, including leaf thickness, epidermal thickness, palisade tissue thickness and sponge tissue thickness were measured by micrometer microscope. The maximum photosynthetic rate, G_s, C_i, T_r and light saturation point(LSP) were significantly different(P<0.05) in the eight species. The difference of epidermal thickness, palisade tissue thickness, upper epidermal stomatal density and lower epidermal stomatal density was significant in the eight trees(P<0.05). Although there was significant difference in photosynthetic characteristics and leaf anatomical structure among the eight species, we found that there was a correlation between them. There was a significant positive correlation between light saturation point and leaf epidermal thickness in the eight species(P<0.01), and the correlation coefficient was 0.78. The intercellular CO₂ concentration was significantly negatively correlated with the upper epidermal stomata density(P<0.05), and the correlation coefficient was -0.65. The maximum photosynthetic rate, R_d, T_r and LSP were not significantly correlated with epidermal thickness, palisade tissue thickness, sponge tissue thickness, upper epidermal stomatal density and epidermis stomatal density(P>0.05). There was no significant correlation between intercellular CO₂ concentration and epidermal thickness, palisade tissue thickness, sponge tissue thickness and epidermis stomatal density(P>0.05). There was no significant correlation between light saturation point and palisade tissue thickness, sponge tissue thickness, upper epidermal stomatal density and epidermis stomatal density(P>0.05). Although there is still a great deal to learn how the leaf anatomical structure effect on physiological process, the measurements of leaf anatomical structure have great potential to provide a better understanding of physiological process.