Taylor Craig R, van Ieperen Wim, Harbinson Jeremy
Horticulture and Product Physiology group, Wageningen University and Research, Wageningen, The Netherlands.
Laboratory of Biophysics, Wageningen University and Research, Wageningen, The Netherlands.
Plant Cell Environ. 2025 Aug;48(8):6102-6117. doi: 10.1111/pce.15557. Epub 2025 May 2.
Far-red light (FR) alone drives photosynthesis poorly, but when combined with shorter wavelengths it enhances photosynthesis beyond the sum of their individual effects-a phenomenon known as the Emerson enhancement effect. This effect is well-established for narrowband PAR-FR mixtures, and recent results show it also occurs within broadband "white" light, though the spectra investigated differed from those observed under natural conditions. In this study, we used simulated sun and foliar shade spectra (SUN and SHADE) during growth and measurements of mature tomato leaves to determine quantum yield for CO assimilation (Φ) on an absorbed light basis under SUN and SHADE, 17 narrowband irradiances, and combinations of SUN or SHADE with the 17 narrowband irradiances. Enhancement was calculated for each of the 53 unique spectra by comparing predicted and measured Φ. This study shows that a 23% enhancement occurs in the simulated SHADE spectrum light and involves the whole spectrum, and in the simulated SUN spectrum enhancement is absent. Further enhancement was observed when narrowband irradiances were added to the SUN or SHADE spectra. The exclusion of the far-red region (> 700 nm) by PAR-based light intensity measurement is particularly problematic in natural, far-red-rich, canopy environments where far-red has surprising photosynthetic utility.
单独的远红光（FR）驱动光合作用的能力很差，但当与较短波长的光结合时，它能增强光合作用，其效果超过各波长光单独作用的总和——这一现象被称为埃默森增强效应。这种效应在窄带光合有效辐射-远红光混合物中已得到充分证实，最近的研究结果表明，它在宽带“白光”中也会出现，尽管所研究的光谱与自然条件下观察到的不同。在本研究中，我们在成熟番茄叶片的生长和测量过程中使用了模拟的阳光和叶片阴影光谱（SUN和SHADE），以确定在SUN和SHADE、17种窄带辐照度以及SUN或SHADE与17种窄带辐照度组合条件下，基于吸收光的CO2同化量子产率（Φ）。通过比较预测的和测量的Φ，计算了53种独特光谱中每一种的增强效果。这项研究表明，在模拟的SHADE光谱光中出现了23%的增强，且涉及整个光谱，而在模拟的SUN光谱中则没有增强。当向SUN或SHADE光谱中添加窄带辐照度时，观察到了进一步的增强。在自然的、富含远红光的冠层环境中，基于光合有效辐射的光强测量排除远红光区域（>700nm）尤其成问题，因为在这种环境中远红光具有惊人的光合效用。
