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为了探明高温胁迫对苋菜(Amaranthus tricolor L.)光合过程的影响,用不同温度(25、30、35、40、45℃)处理苋菜植株1 h后,随即测定了其叶绿素荧光动力学参数和快速光响应曲线特征参数的变化。结果表明:40℃以上高温胁迫下,苋菜叶片的光系统Ⅱ(PSⅡ)潜在光化学效率(Fv/Fo)、最大光化学效率(Fv/Fm)下降;最大荧光(Fm)、光合电子传递速率(ETR)、PSⅡ实际光化学效率(Yield)、光化学淬灭系数(qP)也均有所下降;而初始荧光(Fo)和非光化学淬灭系数(NPQ)在40℃以上高温胁迫下显著上升。叶绿素荧光快速光响应曲线测定结果表明,初始斜率α、最大相对电子传递速率ETRmax和半饱和光强Ik在40℃以上高温胁迫下有所下降。研究表明,40℃以上高温胁迫对苋菜的光能的吸收、转换、光合电子传递和强光耐受能力等均有一定的影响。
In order to find out the effect of high temperature stress on the photosynthetic process of amaranth (Amaranthus tricolor L.), the amaranth plants were treated with different temperature (25,30,35,40,45 ℃) for 1 h, and then the chlorophyll fluorescence kinetic parameters and Variation of characteristic parameters of fast light response curve. The results showed that the potential photochemical efficiency (PSV) and the maximum photochemical efficiency (Fv / Fm) of PSⅡ in amaranth leaves decreased under high temperature stress of more than 40 ℃. The maximal fluorescence (Fm), photosynthetic electron transfer rate ), And the actual photochemical efficiency of PS Ⅱ (Yield) and photochemical quenching coefficient (qP) also decreased. However, the initial fluorescence (Fo) and non-photochemical quenching coefficient (NPQ) increased significantly under high temperature stress above 40 ℃. The results of chlorophyll fluorescence rapid response curve showed that the initial slope α, the maximum relative electron transfer rate ETRmax and the half-saturation intensity Ik decreased under the high temperature of 40 ℃. Studies have shown that high temperature above 40 ℃ on the light energy absorption, transformation, photosynthetic electron transport and light tolerance of amaranth have a certain impact.