UV-B辐射增强对大豆叶绿素荧光特性的影响

利用脉冲振幅调制叶绿素荧光仪测定大豆不同生育期叶片的荧光参数和快速光曲线,以研究UV-B辐射增强对大豆叶绿素荧光特性的影响.结果表明, UV-B辐射增强20%条件下,大豆幼苗期、分枝-开花期和结荚期的叶绿素含量分别降低了5.03%、 7.70%和10.38%;分枝-开花期,F_v/F_m值降低了6.13%;幼苗期和分枝-开花期,有效量子产量(Y)在PAR>366 μmol·(m~2·s)~(-1)时显著降低,最大潜在相对电子传递速率(P_m)分别降低了28.92%和15.49%;但对三叶期和结荚期的Y和P_m无显著影响.UV-B辐射增强使三叶期和幼苗期半饱和光强(l_k)分别降低了21.18%和23.17%;使分枝-开花期的初始斜率(α)降低了21.05%;并显著降低了幼苗期PAR>366 μmol·(m~2·s)~(-1)的非光化学淬灭(NPQ)和分枝-开花期PAR>366 μmol·(m~2·s)~(-1)的光化淬灭(qP).本研究意味着UV-B辐射增强抑制了PSⅡ的电子传递活性,损伤了捕光系统和耗散保护机制,破坏了大豆光合系统,使其光合效率下降.

Influence of Enhanced UV-B Radiation on Chlorophyll Fluorescence Characteristics of Soybean

To investigate the influence of enhanced UV-B radiation on chlorophyll fluorescence characteristics of soybean, pulse amplitude modulation fluorometer was employed to measure the fluorescence parameters and rapid light curves during different growth stages under the condition of simulating 20% enhancement of UV-B. Results showed that enhanced UV-B radiation reduced the chlorophyll contents by 5.03%, 7.70% and 10.38% in seedling, branching-flowering and pod-setting periods, respectively. In branching-flowering period, the value of F_v/F_m decreased by 6.13%. In seedling and branching-flowering periods, effective quantum yield(Y) diminished significantly during PAR>366 μmol·(m~2·s)~(-1), the maximal potential relative electron transport rate (P_m) diminished by 28.92% and 15.49%, respectively. But Y and Pm had no significant difference in 3-leave and pod setting periods. Semi-light saturation points (l_k) were diminished by 21.18% and 23.17% in 3-leave and seedling periods. Initial slope (α) was decreased by 21.05% in branching-flowering period. Enhanced UV-B radiation also significantly reduced non-photochemical quenching (NPQ) during PAR>366 μmol·(m~2·s)~(-1) in seedling period and photochemical quenching (qP) during PAR>366 μmol·(m2·s)~(-1) in branching-flowering period. The results of this study suggested that enhanced UV-B radiation inhibited electron transport activity of PSⅡ, injured light-harvesting systems and dissipative protection mechanisms, damaged photosynthesis system, thus diminished photosynthetic efficiency of soybean.