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为探明UV-B和O3复合胁迫对冬小麦光合作用的影响,开展了UV-B和O3单因子及其复合的大田开顶式气室(OTC)试验(CK,自然空气和UV-B辐射强度;T1,O3含量100 nmol.mol-1±9 nmol.mol-1;T2,UV-B辐射强度相对CK增加10%～10.9%;T3,复合处理组),利用LCpro+光合仪和DIVING-PAM叶绿素荧光仪,测定了不同生育期冬小麦(扬麦16)的气体交换参数和叶绿素荧光参数.结果表明,T1、T2和T3处理冬小麦的Pn、Gs、Tr、Pm和Ik较CK均显著下降,但T3与T1和T2之一或两者在大部分生育期均无显著差异.T2对冬小麦气孔开放和蒸腾作用的抑制程度显著大于T1,而在拔节期T1的Gs和Tr还较CK均显著增加;在整个生育期T1对冬小麦暗呼吸作用(Rd)均有促进,而T2、T3的Rd在大部分时期与CK无差异.T1和T2的Fv/Fm只在孕穗期显著下降,T3除拔节期外均显著低于CK;而T1、T2和T3处理的qP较CK均显著下降,且降幅满足T3>T1>T2.T1、T2和T3处理的NPQ、Y(NPQ)和Y(NO)较CK显著增加,最大增幅满足T3>T1>T2,其中T1和T2的NPQ在灌浆期转而较CK显著下降,而T3的NPQ在扬花期之后即显著下降,且T3的降幅显著大于T1和T2.T1、T2和T3处理的Y(Ⅱ)较CK均显著下降,且降幅满足T3>T1>T2.由此可见,UV-B和O3单因子及其复合胁迫下,冬小麦的气体交换能力、潜在光合能力和光合活性显著下降,光保护机制受到破坏,光能向调节性尤其是向非调节性热耗散的方向分配的比例显著增加,导致冬小麦受到UV-B和过剩光能、O3和过剩光能的双重伤害,并且UV-B和O3对PSⅡ的光保护机制和光能分配存在较为明显复合效应,但复合效应小于两者单独作用时负效应的累加.
To investigate the effects of UV-B and O3 combined photosynthesis on the photosynthesis of winter wheat, UV-B and O3 single-factor and composite open-field OTC (CK, natural air and UV-B radiation The intensity of T1 and O3 was 100 nmol.mol-1 ± 9 nmol.mol-1; the intensity of T2 and UV-B radiation was increased by 10% -10.9% with respect to CK; T3, combined treatment group) PAM chlorophyll fluorescence instrument was used to measure the gas exchange parameters and chlorophyll fluorescence parameters of winter wheat (Yangmai 16) at different growth stages.The results showed that the Pn, Gs, Tr, Pm and Ik of T1, T2 and T3 treatments decreased significantly , But T3 had no significant difference in one or both of T1 and T2 during most of the growth stages.The inhibition of T2 on stomatal opening and transpiration of winter wheat was significantly greater than that of T1, (Rd) of winter wheat increased during the whole growth period T1, while Rd of T2 and T3 had no difference with CK during most of the growth period.The Fv / Fm of T1 and T2 decreased only at booting stage, and T3 Except for the jointing stage, were significantly lower than those of CK. However, the qP of T1, T2 and T3 decreased significantly compared with that of CK, and the decrease of NPQ, Y (NPQ) and Y (NPQ) NO ) Increased significantly compared with that of CK, and the maximum increase of T3> T1> T2, in which the NPQ of T1 and T2 decreased significantly compared with CK at the filling stage, while the NPQ of T3 decreased significantly after flowering, and the decrease of T3 was significantly greater than that of T1 And T2.T1, T2 and T3 treatment Y (Ⅱ) compared with CK were significantly decreased, and the decline to meet the T3> T1> T2. It can be seen, UV-B and O3 single factor and its combined stress, the winter wheat gas exchange Ability, potential photosynthetic capacity and photosynthetic activity significantly decreased, the photoprotection mechanism was destroyed, and the proportion of light energy to the regulatory, especially to the non-regulated heat dissipation significantly increased, resulting in that the winter wheat was affected by UV-B and excess light energy, O3 and excess light energy, and UV-B and O3 have obvious complex effects on photoprotection mechanism and light energy distribution of PSII, but the compound effect is less than the cumulative effect of negative effects of the two alone.