《植物生理学报》 2017, 53(7): 1279-1286

密植对薄荷叶片光系统II功能的影响

李涛^1,2, 姜闯道^2,*

¹山西农业大学林学院植物科学系, 山西太谷030801; ²中国科学院植物研究所北方资源植物重点实验室, 北京100093

通信作者：姜闯道；E-mail: jcdao@ibcas.ac.cn

摘　要：

通过气体交换、荧光诱导动力学和荧光淬灭动力学等技术探讨了种植密度对薄荷光合特性及光系统II (PSII)功能的影响。结果显示: 增加种植密度会显著降低单株的总叶面积、叶绿素含量和光饱和光合速率, 但对叶片的表观量子效率(AQY)影响较小。随着种植密度的升高, 叶片的快速叶绿素荧光诱导动力学曲线(OJIP)明显改变, 但最大光化学效率(φ_Po)变化不大; 进一步分析表明, 叶片单位截面有活性反应中心的数量(RC/CS₀)和单位面积吸收(ABS/CS₀)、捕获(TR₀/CS₀)及用于电子传递的能量(ET₀/CS₀)均下降。在光下, 密植还诱导PSII实际光化学量子效率(Φ_PSII)下降, 而非光化学淬灭(NPQ)升高。因此, 密植抑制了薄荷叶片的光合能力和PSII功能, 并进而导致光下PSII的光能利用下降和激发能耗散增强。

关键词：薄荷; 光合速率; 叶绿素荧光; 激发能分配

收稿：2017-04-17   修定：2017-06-23

资助：国家自然科学基金(31571576)和山西农业大学科技创新基金及博士科研启动项目(2015YJ25)。

Effects of close planting on photosystem II functions in Mentha haplocalyx leaves

LI Tao^1,2, JIANG Chuang-Dao^2,*

¹Department of Plant Science, College of Forestry, Shanxi Agricultural University, Taigu 030801, Shanxi, China; ²Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China

Corresponding author: JIANG Chuang-Dao; E-mail: jcdao@ibcas.ac.cn

Abstract:

Gas exchange, prompt fluorescence and fluorescence quenching kinetics were investigated to explore the effects of close planting on photosynthetic characteristics and the photosystem II (PSII) function of Mentha haplocalyx in this study. The results showed that close planting not only induced a significant decrease in leaf area in individual plant, but also resulted in a marked decline in chlorophyll content and the net photosynthetic rate (P_n), while the apparent quantum yield (AQY) exhibited a slight decrease. With increased planting density, the chlorophyll a fluorescence transients (OJIP) showed a distinct changed and the maximum quantum yield of primary photochemistry (φ_Po) remained stable. Relative to a low planting density, plants grown at a high planting density had lower the absorption flux per excited cross-section (ABS/CS₀), the trapped energy flux per excited cross-section (TR₀/CS₀) and the electron transport flux per excited cross-section (ET₀/CS₀) as well as the amount of active PSII reaction centers per excited cross-section (RC/CS₀). Moreover, the actual photosystem II efficiency (Φ_PSII) declined with increased planting density, whereas the non-photochemical fluorescence quenching (NPQ) increased. Accordingly, we suggest that the depression of photosynthetic capacity caused by close planting changes the PSII function, which further limits the light utilization and enhances the dissipation of excited energy.

Key words: Mentha haplocalyx Briq; photosynthetic rate; chlorophyll a fluorescence; excitation energy distribution