Table_2_Integrating Morphological and Physiological Responses of Tomato Plants to Light Quality to the Crop Level by 3D Modeling.pdf

Next to its intensity, the spectral composition of light is one of the most important factors affecting plant growth and morphology. The introduction of light emitting diodes (LEDs) offers perspectives to design optimal light spectra for plant production systems. However, knowledge on the effects of light quality on physiological plant processes is still limited. The aim of this study is to determine the effects of six light qualities on growth and plant architecture of young tomato plants, and to upscale these effects to the crop level using a multispectral, functional-structural plant model. Young tomato plants were grown under 210 μmol m-2 s-1 blue, green, amber, red, white or red/blue (92%/8%) LED light with a low intensity of sunlight as background. Plants grown under blue light were shorter and developed smaller leaves which were obliquely oriented upward. Leaves grown under blue light contained the highest levels of light harvesting pigments, but when exposed to blue light only, they had the lowest rate of leaf photosynthesis. However, when exposed to white light these leaves had the highest rate of photosynthesis. Under green light, tomato plants were taller and leaves were nearly horizontally oriented, with a high specific leaf area. The open plant structure combined with a high light transmission and reflection at the leaf level allowed green light to penetrate deeper into the canopy. Plants grown under red, amber and white light were comparable with respect to height, leaf area and biomass production. The 3D model simulations indicated that the observed changes in plant architecture had a significant impact on light absorbance at the leaf and crop level. The combination of plant architecture and spectrum dependent photosynthesis was found to result in the highest rate of crop photosynthesis under red light in plants initially grown under green light. These results suggest that dynamic light spectra may offer perspectives to increase growth and production in high value production systems such as greenhouse horticulture and vertical farming.

除光强之外，光的光谱组成是影响植物生长与形态建成的最关键因素之一。发光二极管（Light Emitting Diodes, LEDs）的问世为植物生产系统的最优光光谱设计提供了可行方案。然而，当前关于光质对植物生理过程影响的认知仍较为有限。本研究旨在明确六种光质对番茄幼苗生长及株型的调控效应，并借助多光谱功能-结构植物模型将这些效应拓展至作物尺度。
番茄幼苗被置于210 μmol·m⁻²·s⁻¹的蓝光、绿光、琥珀光、红光、白光或92%红光/8%蓝光配比的LED光源下培养，辅以低强度太阳光作为背景光。在蓝光环境下培养的植株更为矮壮，叶片尺寸更小且呈向上斜生状态。蓝光培养的叶片中捕光色素含量最高，但仅暴露于蓝光时，其叶片光合速率最低；而当这些叶片切换至白光环境时，光合速率则达到峰值。在绿光环境下培养的番茄植株更高，叶片近乎水平分布，比叶面积较高。开放的株型配合叶片层面的高光透射与反射特性，使得绿光能够更深地穿透冠层。在红光、琥珀光及白光环境下培养的植株，在株高、叶面积及生物量积累方面表现相近。
三维模型模拟结果显示，观测到的株型变化对叶片及作物尺度的光吸收具有显著影响。研究发现，株型与光谱依赖性光合过程的协同作用，使得预先在绿光环境下培养的植株在红光环境下的作物光合速率达到最高。上述结果表明，动态光谱调控有望为提升温室园艺、垂直农场等高附加值生产系统的作物生长与产量提供新的可行路径。