摘要:为探究干旱胁迫及复水后外源褪黑素对玉米叶片光合作用的影响和调控机制。以玉米陕单609盆栽苗为试验材料，叶面喷施褪黑素100 μmol/L在重度干旱和复水后分别测定了生物量、净光合速率（P_n）以及光合电子传递速率等指标。结果显示：外源褪黑激素可减轻干旱胁迫引起的生长抑制；外源褪黑激素处理的植株表现出比未处理植株更高的P_n、气孔导度（G_s）以及更低的胞间CO₂浓度（C_i）；外源褪黑素增加了干旱胁迫下OJIP曲线的荧光参数φ_P0、φ_E0、ψ₀以及光合性能指数PI_abs；外源褪黑素也提高了干旱胁迫下叶片PSⅡ和PSI有效量子产量[Y（Ⅱ），Y（I）]；也增加了干旱胁迫下叶片的PSⅡ和PSI电子传递速率（ETRⅡ，ETRI），但降低了干旱胁迫下叶片PSI受体侧限制[Y（NA）]和供体侧限制[Y（ND）]。表明外源褪黑素对干旱胁迫下光抑制具有一定的缓解作用。复水后，干旱胁迫下褪黑素处理玉米叶片各参数都恢复到对照水平；而干旱胁迫处理玉米叶片各参数复水后不能完全恢复。可见，喷施褪黑素不仅缓解干旱胁迫对玉米PSⅡ和PSI结构和功能的损伤，而且能加速复水后光合机构功能的恢复，促进玉米植株恢复性生长。因此喷施褪黑素加强玉米叶片光合作用适应干旱环境是一种重要的调控方式。



Abstract:In order to explore the effects of exogenous melatonin on photosynthetic apparatus of maize leaves under drought stress and rewatering and clarify the physiological mechanisms involved, the biomass, net photosynthetic rate (P_n), and photosynthetic electron transfer rate in seedlings of maize shaandan609 with or without 100 μmol/L melatonin application were analyzed after severe drought and rewatering.. The results showed that exogenous melatonin alleviated growth inhibition caused by drought stress. Further investigation demonstrated that, under drought condition, melatonin-treated plants indicated higher P_n and stomatal conductance (G_s), as well as lower intercellular CO₂ concentration (C_i) than those untreated plants. In addition, exogenous melatonin increased the fluorescence parameters φ_P0, φ_E0, ψ₀ and photosynthetic performance index PI_abs of OJIP curve under drought stress. It also improved the effective quantum yield of PSⅡ and PSⅡ under drought stress [Y(Ⅱ), Y(I)]. The melatonin treatment decreased the PSI receptor side limitation [Y(NA)] and donor side limitation [Y(ND)] of leaf photosynthetic apparatus after drought stress. Moreover, exogenous melatonin increased the electron transfer rate (ETRⅡ, ETRI) of PSⅡ and PSⅡ in maize leaves under drought stress, indicating that exogenous melatonin could alleviate photo-inhibition under drought stress. After rewatering, all the parameters of maize leaves treated with melatonin returned to the control level under drought stress, while the parameters of maize leaves treated with drought stress could not recover after rehydration. It can be concluded that exogenous spraying melatonin can not only alleviate the damage of PSⅡ and PSI structure and function of maize caused by drought stress, but also accelerate the recovery of photosynthetic apparatus function after rewatering, resulting in improving the recovery of maize seedling growth. Therefore, exogenous melatonin application could be an important regulation mode to adapt to arid environment by enhancing photosynthesis of maize leaves.





PDF全文下载地址:

https://www.ecologica.cn/stxb/article/pdf/stxb202003310763