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为给O3等大气污染物胁迫下我国粮食生产和安全评估提供依据,利用开顶式气室(OTC)开展了3种O3熏蒸水平的大田试验(空气,CK;100 nL.L-1,T1;150 nL.L-1,T2),采用D iving-PAM叶绿素荧光仪和LC pro+光合仪测定了冬小麦(扬麦13)不同生育期的叶绿素荧光及气体交换参数.结果表明,T1的Fv/Fm均高于0.8,Pm、qP、(1-qP)/NPQ及Y(NO)与CK相似,NPQ及Y(NPQ)分别较CK上升13.5%~29.0%和13.3%~22.7%,实际光化学效率在自然光下(快速光曲线,RLC)和暗适应后(诱导曲线达稳态时,IC)分别下降4.6%~7.6%和11.3%~19.3%,Pn与Gs分别下降8.0%~9.8%和11.0%~23.1%,Ls在抽穗期和扬花期高于CK,在灌浆期和成熟期低于CK;T2的Fv/Fm均略低于0.8,Y(NO)、(1-qP)/NPQ及ci分别较CK增加37.9%~75.6%、157.1%~325.8%和3.4%~18.1%,实际光化学效率在RLC和IC条件下分别下降10.2%~13.6%和21.4%~29.1%,Pn、Ls、qP、Pm、NPQ及Y(NPQ)分别下降28.1%~39.9%、5.2%~21.3%、15.8%~30.4%、27.6%~45.6%、33.3%~52.9%和5.7%~17.9%.O3胁迫显著降低了冬小麦的光合能力,其胁迫效应和作用机制在生长季内呈动态变化;T1的Fv/Fm下降是对NPQ增加的响应,Pn与实际光化学效率降低是保护性调节的结果,其抗氧化系统及热耗散机制足以保护PSⅡ反应中心免遭光伤害;T2的CO2同化与QA重新氧化受限,热耗散机制受损,其光合能力下降是光合系统受到O3与过剩光能双重伤害的结果;O3损伤冬小麦PSⅡ的临界值在100~150 nL.L-1之间,接近100 nL.L-1,Fv/Fm难以指示O3对冬小麦的胁迫.尽管冬小麦对高浓度O3具有一定适应能力,地表O3浓度升高仍然是我国粮食生产中面临的一个重要的问题.
In order to provide the basis for food production and safety assessment under the stress of O3 and other air pollutants in our country, three O3 fumigation field trials (air, CK, 100 nL.L-1, T1 ; 150 nL.L-1, T2), the chlorophyll fluorescence and gas exchange parameters of winter wheat (Yangmai 13) at different growth stages were measured by Diverving-PAM chlorophyll fluorescence and LC pro + photosynthesis. The results showed that the Fv / Fm were higher than 0.8, Pm, qP, (1-qP) / NPQ and Y (NO) were similar to CK, NPQ and Y (NPQ) increased by 13.5% -29.0% and 13.3% -22.7% The efficiency decreased by 4.6% -7.6% and 11.3% -19.3% under natural light (fast light curve, RLC) and dark adaptation (induction curve reached steady state, respectively) while Pn and Gs decreased by 8.0-9.8% 11.0% ~ 23.1%. Ls was higher than CK at heading and flowering stage, but lower than CK at filling stage and mature stage. Fv / Fm of T2 was slightly lower than 0.8, Y (NO), (1-qP) And ci increased by 37.9% -75.6%, 157.1% -252.8% and 3.4% -18.1%, respectively, compared with CK. The actual photochemical efficiency decreased by 10.2% -13.6% and 21.4% -29.1% under RLC and IC conditions respectively. , QP, Pm, NPQ and Y (NPQ) decreased by 28.1% -39.9%, 5.2% -21.3%, 15.8% -30.4%, 27.6% -45.6%, 33.3% -52.9 % And 5.7% -17.9%, respectively.O3 stress significantly reduced the photosynthetic capacity of winter wheat, and the stress effect and mechanism of dynamic stress were dynamic during the growing season. The decrease of Fv / Fm of T1 was the response to the increase of NPQ. The correlation between Pn and actual photochemical efficiency Decrease is the result of protective regulation. Its antioxidant system and heat dissipation mechanism are enough to protect the PSⅡ reaction center from light damage. T2 assimilation and QA reoxidation are limited, heat dissipation mechanism is impaired and photosynthetic capacity is decreased Photosynthetic system was affected by both O3 and excess light energy. The critical value of PS3 in O3-damaged winter wheat was between 100-150 nL.L-1, close to 100 nL.L-1, indicating that Fv / Fm could not indicate O3 stress on winter wheat Although winter wheat has certain adaptability to high concentration O3, the increase of surface O3 concentration is still an important issue in the grain production in our country.