高粱、紫苏叶脉密度与光合特性的关系

Relationship Between Photosynthetic Characteristics and Leaf Vein Density in Sorghum bicolor and Perilla frutescens

叶脉是植物叶片光合作用水分输送的重要结构。为阐述叶脉与光合特性之间的关系,以C4植物高粱(Sorghum bicolor)、C3植物紫苏(Perilla frutescens)为实验材料研究了叶脉密度和光合特性之间的关系。结果表明,与紫苏相比,高粱叶片叶脉密度大,导水能力强,蒸腾速率高,但气孔密度小。进一步分析表明,高粱叶片近轴侧气孔密度占总气孔的比例明显高于紫苏。叶脉密度大的高粱具有较高的净光合速率;而紫苏叶脉密度小,净光合速率也较低。由此表明,较高的叶脉密度有利于支持较高的光合速率,但研究表明叶脉密度和气孔密度可能不存在严格的协同变异关系。研究结果对理解植物光合作用适应有重要意义。

Leaf vein is an important structure for plant photosynthesis and water transportation. In this study, leaf vein density and photosynthetic characteristics were examined to explore the relationship between them in Sorghum bicolor and Peri//a frutescens seedlings. Compared with perilla, sorghum leaves had higher leaf vein density, stomatal conduc- tance （Gs） and leaf hydraulic conductance （Kleaf）. While perilla leaves had higher stomatal density than sorghum leaves. For sorghum leaves, the proportion of stomata on the adaxial side accounted for 38.4% of the total stomata, which was significantly higher than that in perilla leaves. Sorghum leaves developed with higher vein density had higher net photo- synthetic rate, whereas perilla leaves developed with lower vein density have lower net photosynthetic rate. Therefore, high photosynthetic rate in sorghum may be related to high vein density. However, there was no rigidly collaborative variation between leaf vein density and stomatal density. These conclusions are important for the study of photosynthetic adaptation to water availability.