Huang Guanjun, Zhang Qiangqiang, Wei Xinghai, Peng Shaobing, Li Yong
Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural UniversityWuhan, China.
Front Plant Sci. 2017 Jun 6;8:945. doi: 10.3389/fpls.2017.00945. eCollection 2017.
Nitrogen is one of the most important elements for plants and is closely related to photosynthesis. High temperature stress significantly inhibits photosynthesis under both steady-state and flecked irradiance. However, it is not known whether nitrogen can affect the decrease in photosynthesis caused by high temperature, especially under flecked irradiance. In the present study, a pot experiment was conducted under two nitrogen (N) supplies with rice plants, and the steady-state and dynamic photosynthesis rates were measured under 28 and 40°C. High temperature significantly increased leaf hydraulic conductance () under high N supply (HN) but not under low N supply (LN). The increased maintained a constant leaf water potential (Ψ) and steady-state stomatal conductance () under HN, while the Ψ and significantly decreased under high temperature in LN conditions. This resulted in a more severe decrease in steady-state photosynthesis () under high temperature in the LN conditions. After shifting from low to high light, high temperature significantly delayed the recovery of photosynthesis, which resulted in more carbon loss under flecked irradiance. These effects were obtained under HN to a lesser extent than under LN supply. Therefore, it is concluded that nitrogen can alleviate the inhibition of photosynthesis caused by high temperature stress under both steady-state and flecked irradiance.
氮是植物最重要的元素之一，与光合作用密切相关。高温胁迫在稳态和光斑照射下均显著抑制光合作用。然而，尚不清楚氮是否会影响高温导致的光合作用下降，尤其是在光斑照射下。在本研究中，对水稻植株在两种供氮水平下进行了盆栽试验，并在28℃和40℃下测定了稳态和动态光合速率。在高氮供应（HN）下高温显著增加了叶片水力导度（），而在低氮供应（LN）下则没有。在HN条件下，增加的维持了恒定的叶片水势（Ψ）和稳态气孔导度（），而在LN条件下高温时Ψ和显著下降。这导致在LN条件下高温时稳态光合作用（）下降更严重。从低光转换到高光后，高温显著延迟了光合作用的恢复，这导致在光斑照射下碳损失更多。这些效应在HN条件下比在LN供应下程度更小。因此，得出结论，在稳态和光斑照射下，氮均可缓解高温胁迫对光合作用的抑制。
