Chu Run, Zhang Qin-Hu, Wei Yu-Zhen
College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou, 730070, China.
Photosynth Res. 2022 Sep;153(3):177-189. doi: 10.1007/s11120-022-00933-8. Epub 2022 Jul 14.
Iris tectorum Maxim. is an important plant that plays a very crucial role in the ecological welfare of wetlands. In this study, the effects of different intensities of UV-B radiation on the growth, photosynthetic pigment content, chlorophyll fluorescence characteristics, chloroplast ultrastructure, and gas exchange parameters of Iris tectorum Maxim. were studied. The results showed that enhanced UV-B radiation had a significant influence on the above-mentioned parameters of iris. Compared with the control, enhanced UV-B radiation caused certain damage to the leaf appearance. With the increasing intensity of radiation, the apparent damage degree became more serious. Enhanced UV-B radiation significantly decreased leaf chlorophyll contents, and the effect accumulated with the exposure time. Enhanced UV-B radiation increased Fo, significantly increased the non-photochemical quenching coefficient NPQ, reduced PSII and Qp, and significantly decreased the Fm, Fv/Fm, and Fv/Fo in leaves. The effect of UV-B radiation on PSII destruction of Iris tectorum Maxim. increased as the radiation intensity increased and the exposure time prolonged. The chloroplast structure was damaged under the enhanced UV-B radiation. More specifically, thylakoid lamellae were distorted, swelling and even blurred, and a large number of starch granules appeared. The effect of the high intensity of radiation on chloroplast ultrastructure was greater than that of lower intensity. Enhanced UV-B radiation reduced significantly the net photosynthetic rate, stomatal conductance, and transpiration rate, and the degree of degradation increased with the increasing irradiation intensity. However, the intercellular CO content increased, which suggests that the main reason for the decrease of photosynthetic rate was the non-stomatal factors.
鸢尾是一种重要的植物，在湿地生态福祉中发挥着至关重要的作用。本研究探讨了不同强度的UV-B辐射对鸢尾生长、光合色素含量、叶绿素荧光特性、叶绿体超微结构及气体交换参数的影响。结果表明，增强的UV-B辐射对鸢尾上述参数有显著影响。与对照相比，增强的UV-B辐射对叶片外观造成一定损伤，且随着辐射强度增加，表观损伤程度加重。增强的UV-B辐射显著降低叶片叶绿素含量，且该效应随照射时间累积。增强的UV-B辐射使Fo升高，非光化学猝灭系数NPQ显著增加，PSII和Qp降低，叶片中Fm、Fv/Fm和Fv/Fo显著下降。UV-B辐射对鸢尾PSII破坏的影响随辐射强度增加和照射时间延长而增大。增强的UV-B辐射下叶绿体结构受损，具体表现为类囊体片层扭曲、肿胀甚至模糊，且出现大量淀粉粒。高强度辐射对叶绿体超微结构的影响大于低强度辐射。增强的UV-B辐射显著降低净光合速率、气孔导度和蒸腾速率，且降解程度随辐射强度增加而增大。然而，细胞间CO含量增加，这表明光合速率下降的主要原因是非气孔因素。
