| Summary: | Nitrogen dioxide (NO<sub>2</sub>) is recognized as a toxic gaseous air pollutant. However, atmospheric NO<sub>2</sub> can be absorbed by plant leaves and subsequently participate in plant nitrogen metabolism. The metabolism of atmospheric NO<sub>2</sub> utilizes and consumes the light energy that leaves absorb. As such, it remains unclear whether the consumption of photosynthetic energy through nitrogen metabolism can decrease the photosynthetic capacity of plant leaves or not. In this study, we fumigated mulberry (<i>Morus alba</i> L.) plants with 4 μL·L<sup>−1</sup> NO<sub>2</sub> and analyzed the distribution of light energy absorbed by plants in NO<sub>2</sub> metabolism using gas exchange and chlorophyll a fluorescence technology, as well as biochemical methods. NO<sub>2</sub> fumigation enhanced the nitrogen metabolism of mulberry leaves, improved the photorespiration rate, and consumed excess light energy to protect the photosynthetic apparatus. Additionally, the excess light energy absorbed by the photosystem II reaction center in leaves of mulberry was dissipated in the form of heat dissipation. Thus, light energy was absorbed more efficiently in photosynthetic carbon assimilation in mulberry plants fumigated with 4 μL·L<sup>−1</sup> NO<sub>2</sub>, which in turn increased the photosynthetic efficiency of mulberry leaves.
|
|---|
