Zheng You-Fei, Zhang Jin-En, Wu Rong-Jun, Liu Rui-Na, Zhao Ze, Hu Cheng-Da, Xu Wei-Min, Zhao Chun-Xia, Yao Juan
Jiangsu Key Laboratory of Meteorological Disaster, Nanjing 210044, China.
Huan Jing Ke Xue. 2011 Oct;32(10):3023-32.
Experiments were conducted under open-top-chambers conditions to assess the photosynthetic responses of wheat plants (Triticum aestivum L., YangMail6) to supplemental UV-B radiation (10%-10.9% higher then control group, T1) and enhanced ozone [(100 +/- 9) nmol x mol(-1), T2], separately and in combination (combination treatment, T3), making use of LCpro + Portable Photosynthesis System and DIVING-PAM Fluorometer to determine gas exchange and chlorophyll fluorescence parameters. Results indicated that P(n), G(s), T(r), P(m) and I(k) of T1, T2 and T3 treatments decreased significantly compared to CK (control group, natural air and UV-B radiant intensity condition), while there were no differences between T3 and T1 or T2 or both in major growth stages. UV-B fiercely inhibited the stomatal conductance and transpiration of plants, while T1 stimulated stomata opening and transpiration in jointing stage. Dark respiration (R(d)) of T1 was increased, while no significance difference was found between T2 and CK or T3 and CK in most stages. T1 and T2 reduced F(v)/F(m) value only in booting stage, while T3 was significant lower than CK except jointing stage. qP value declined significantly in treatments of T1, T2 and T3 as Compared to CK, with decreasing amplitude occurring in the order T3 > T1 > T2. NPQ, Y (NPQ), Y (NO) value of T1, T2 and T3 treatments increased significantly compared to CK, with maximum increasing amplitude occurring in the order T3 > T1 > T2, of which NPQ of T1 and T2 turned to decrease since filling stage, and T3 turned to decrease since flowering stage to a greater degree than T1 and T2. T1, T2 and T3 also caused significance reduction in Y (II), with reducing amplitude occurring in the order T3 > T1 > T2. Obviously, supplemental UV-B radiation and enhanced ozone caused a significant decrease in gas exchange capacity, maximum photochemical capacity and photosynthetic activity of winter wheat, and the photoprotective mechanism was damage, leading to greater proportion of excitation energy dissipated in the form of non-regulated heat and fluorescence. The photosystems of winter wheat were damaged by both excess energy and UV-B or excess energy and O3, or excess energy, UV-B and O3 together. UV-B and O3 in combination enhanced the negative effects on photo-protective mechanisms and excitation energy distribution in PS II compared to UV-B or O3 alone, while the interactive effects were less than addition.
在开顶式气室条件下进行实验，利用LCpro +便携式光合作用系统和DIVING-PAM荧光仪测定气体交换和叶绿素荧光参数，以评估小麦植株（扬麦6号，Triticum aestivum L.）对补充UV-B辐射（比对照组高10%-10.9%，T1）和增强臭氧[（100±9）nmol·mol⁻¹，T2]单独及组合处理（组合处理，T3）的光合响应。结果表明，与CK（对照组，自然空气和UV-B辐射强度条件）相比，T1、T2和T3处理的净光合速率（P(n)）、气孔导度（G(s)）、蒸腾速率（T(r)）、最大光合速率（P(m)）和光饱和点（I(k)）均显著降低，而在主要生育期T3与T1或T2或两者之间无差异。UV-B强烈抑制植物的气孔导度和蒸腾作用，而T1在拔节期刺激气孔开放和蒸腾。T1的暗呼吸速率（R(d)）增加，而在大多数阶段T2与CK或T3与CK之间未发现显著差异。T1和T2仅在孕穗期降低F(v)/F(m)值，而T3除拔节期外显著低于CK。与CK相比，T1、T2和T3处理的qP值显著下降，下降幅度依次为T3>T1>T2。T1、T2和T3处理的NPQ、Y(NPQ)、Y(NO)值与CK相比显著增加，最大增加幅度依次为T3>T1>T2，其中T1和T2的NPQ自灌浆期开始下降，T3自开花期开始下降且下降幅度大于T1和T2。T1、T2和T3也导致Y(II)显著降低，降低幅度依次为T3>T1>T2。显然，补充UV-B辐射和增强臭氧导致冬小麦的气体交换能力、最大光化学能力和光合活性显著下降，光保护机制受损，导致更大比例的激发能以非调节热和荧光的形式耗散。冬小麦的光合系统受到过量能量和UV-B或过量能量和O3或过量能量、UV-B和O3共同作用的损害。与单独的UV-B或O3相比，UV-B和O3组合增强了对光保护机制和PS II中激发能分配的负面影响，而交互作用小于相加作用。
