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

Abstract

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.

LED light gradient as a screening tool for light quality responses in model plant species

“…In S. lycopersicum, we observed a strong increase in shoot height under higher Red:Blue ratios. This phenotype, which is a consequence of higher internode elongation, is consistent with previous studies showing that blue wavelengths inhibit stem elongation in phylogenetically distant eudicot species such as lettuce, soybean, and tomato (52)(53)(54). We also found differences in color proxies (TGI, chlorophyll measurements) along the color gradient, which are consistent with a previous report showing that blue light exposure increases chlorophyll content in tomato leaves (54).…”

Supplemental Light-Emitting Diode Inter-Lighting Increases Tomato Fruit Growth Through Enhanced Photosynthetic Light Use Efficiency and Modulated Root Activity

“…The complexity is also increased by the fact that leaf orientation can be modulated by light to increase light interception (Sarlikioti et al, 2011) and this will ultimately affect the light distribution in the canopy and the light interception by the canopy (de Visser et al, 2014). Moreover, LED lamps with different spectra can also modulate the leaf angle to affect light absorption at the leaf and crop levels (Dieleman et al, 2019).…”

Subtle changes in solar radiation under a green-to-red conversion film affect the photosynthetic performance and chlorophyll fluorescence of sweet pepper

“…The research on the effects of light quality on plants has mostly focused on growth and morphology (Smith 1982, Patil et al 2001, Li et al 2003, Niinemets 2010, Stanton et al 2010, Dieleman et al 2019. Recently, research focusing on photosynthetic capacity according to light quality using artificial irradiance has been reported in detail.…”