土壤干旱和强光交互作用对青藏高原高山嵩草光合功能的影响

植物对单一环境因子的响应常会因另一因子存在而被修饰。本文主要采用叶绿素荧光图像分析技术,研究了土壤干旱对高山嵩草(Kobresia pygmaea)叶片光合功能的影响及与强光的交互效应。结果表明:土壤干旱胁迫可引起叶绿素a(Chl a)含量和Chla/b比值的降低,对总叶绿素(Chl a+b)含量无影响。高光强可导致PSII最大效率(F_v'/F_m')、PSII运行效率(F_q'/F_m')和PSII效率因子(F_q'/F_v')的显著降低,且F_v'/F_m'和F_q'/F_m'的降低为土壤干旱所加剧;非光化学猝灭系数(NPQ)和光化学效率的相对限制(L(PFD))随光强增大显著增加,也为干旱胁迫所加剧;PSII反应中心开放比率(qL)随光强的增大而降低,土壤干旱时降低趋势较小。方差分析表明,光强是影响光合机构光能利用和耗散的主要因素;PSII非光化学能量耗散存在着两种胁迫因子的交互效应,但F_q'/F_m'和L(PFD)则无。证实,高山嵩草能快速响应环境光强的变化,并对土壤干旱胁迫具有较强的耐受性,非光化学能量耗散的加强是光合功能有效维系的保护策略。

Interaction Effect of Soil Drought and Strong Light on Photosynthetic Performance of Kobresia Pygmaea in Qinghai-Tibetan Plateau

Plant response to a single environmental factor is often modified by another factor.Kobresia pygmaea was collected from the Alpine Grassland Ecosystem Research Station in the region of Three-RiverSource.The chlorophyll fluorescence imaging of leaves was used to determine the interaction effects between soil drought and strong light besides measurement of photosynthetic pigments.The results showed that there was no difference in total chlorophyll contents (Chl a+b),and that chlorophyll a contents (Chl a) and the ratio of chlorophyll a to b (Chl a/b) decreased in soil drought treatment.The PSII maximum and operating efficiency (Fv'/Fm' and Fq'/Fm') and the PSII efficiency factor (Fq'/Fv') were significantly influenced by actinic light intensity,and the decrease of F(/Fm' and Fq'/Fm' were intensified by the treatment of soil drought.Non-photochemical quenching coefficient (NPQ) and relative limitation of PSII photochemical efficiency (L(PFD)) increased with the enhancement of actinic light intensity,and these trends were aggravated in soil drought treatment.GLM univariate analysis indicated that light intensity was the main factor,and excepting Fq'/Fm' and L(PFD),the fluorescence parameters of NPQ and Fv'/Fm' exhibited interaction effect among actinic light and soil drought treatments.The results demonstrated that K.pygmaea could quickly respond to environmental light variations and had a strong tolerance to soil drought stress.The improvement of dissipation of non-photochemical energy was one of the important strategies for K.pygmaea to maintain effective performance of photosynthetic apparatus in alpine environments.