Dezhou University, Dezhou, China.
Shandong Agricultural University, Taian, China.
PeerJ. 2022 Mar 10;10:e13087. doi: 10.7717/peerj.13087. eCollection 2022.
As a fundamental metabolism, leaf photosynthesis not only provides necessary energy for plant survival and growth but also plays an important role in global carbon fixation. However, photosynthesis is highly susceptible to environmental stresses and can be significantly influenced by future climate change.
In this study, we examined the photosynthetic responses of (. ) to three precipitation treatments (control, decreased 30%, and increased 30%) under two thermal regimes (ambient temperature and +4 °C) in environment-controlled chambers.
Our results showed that the net CO assimilation rate ( ), maximal rate of Rubisco ( ), maximal rate of ribulose-bisphosphate (RuBP) regeneration ( ) and chlorophyll (Chl) content were enhanced under increased precipitation condition, but were declined drastically under the condition of water deficit. The increased precipitation had no significant effect on malondialdehyde (MDA) content ( > 0.05), but water deficit drastically enhanced the MDA content by 10.1%. Meanwhile, a high temperature inhibited the positive effects of increased precipitation, aggravated the adverse effects of drought. The combination of high temperature and water deficit had more detrimental effect on . than a single factor. Moreover, non-stomatal limitation caused by precipitation change played a major role in determining carbon assimilation rate. Under ambient temperature, Chl content had close relationship with (R = 0.86, < 0.01). Under high temperature, was ralated to MDA content (R = 0.81, < 0.01). High temperature disrupted the balance between and (the ratio of to decreased from 1.88 to 1.12) which resulted in a negative effect on the photosynthesis of . . Furthermore, by the analysis of Chl fluorescence, we found that the xanthophyll cycle-mediated thermal dissipation played a major role in PSII photoprotection, resulting in no significant change on actual PSII quantum yield ( ) under both changing precipitation and high temperature conditions.
Our results highlight the significant role of precipitation change in regulating the photosynthetic performance of . under elevated temperature conditions, which may exacerbate the drought-induced primary productivity reduction of . under future climate scenarios.
作为一种基本的代谢过程，叶片光合作用不仅为植物的生存和生长提供了必要的能量，而且在全球碳固定中起着重要作用。然而，光合作用对环境胁迫非常敏感，并且会受到未来气候变化的显著影响。
在本研究中，我们在环境控制室中，使用两种热环境（环境温度和+4°C）和三种降水处理（对照、减少 30%和增加 30%），对（）的光合作用响应进行了研究。
我们的结果表明，在增加降水条件下，净 CO2 同化率（）、Rubisco 最大速率（）、核酮糖-1,5-二磷酸（RuBP）最大再生速率（）和叶绿素（Chl）含量均得到增强，但在水分亏缺条件下则大幅下降。增加降水对丙二醛（MDA）含量（>0.05）没有显著影响，但水分亏缺使 MDA 含量大幅增加 10.1%。同时，高温抑制了增加降水的积极影响，加剧了干旱的不利影响。高温和水分亏缺的组合对（）的不利影响比单一因素更大。此外，降水变化引起的非气孔限制在决定碳同化率方面起着主要作用。在环境温度下，Chl 含量与（R = 0.86，<0.01）密切相关。在高温下，与 MDA 含量（R = 0.81，<0.01）相关。高温破坏了（）与（）之间的平衡（从 1.88 降低到 1.12），这对（）的光合作用产生了负面影响。此外，通过叶绿素荧光分析，我们发现叶黄素循环介导的热耗散在 PSII 光保护中起着主要作用，因此在降水变化和高温条件下，实际 PSII 量子产量（）没有明显变化。
我们的结果强调了降水变化在调节升高温度条件下（）光合作用性能方面的重要作用，这可能会加剧未来气候情景下干旱引起的（）初级生产力降低。
