LED Lighting – Modification of Growth, Metabolism, Yield and Flour Composition in Wheat by Spectral Quality and Intensity

Abstract

The use of light-emitting diode (LED) technology for plant cultivation under controlled environmental conditions can result in significant reductions in energy consumption. However, there is still a lack of detailed information on the lighting conditions required for optimal growth of different plant species and the effects of light intensity and spectral composition on plant metabolism and nutritional quality. In the present study, wheat plants were grown under six regimens designed to compare the effects of LED and conventional fluorescent lights on growth and development, leaf photosynthesis, thiol and amino acid metabolism as well as grain yield and flour quality of wheat. Benefits of LED light sources over fluorescent lighting were manifested in both yield and quality of wheat. Elevated light intensities made possible with LEDs increased photosynthetic activity, the number of tillers, biomass and yield. At lower light intensities, blue, green and far-red light operated antagonistically during the stem elongation period. High photosynthetic activity was achieved when at least 50% of red light was applied during cultivation. A high proportion of blue light prolonged the juvenile phase, while the shortest flowering time was achieved when the blue to red ratio was around one. Blue and far-red light affected the glutathione- and proline-dependent redox environment in leaves. LEDs, especially in Blue, Pink and Red Low Light (RedLL) regimens improved flour quality by modifying starch and protein content, dough strength and extensibility as demonstrated by the ratios of high to low molecular weight glutenins, ratios of glutenins to gliadins and gluten spread values. These results clearly show that LEDs are efficient for experimental wheat cultivation, and make it possible to optimize the growth conditions and to manipulate metabolism, yield and quality through modification of light quality and quantity.

Effects of light intensity and spectral composition on the growth and metabolism of spinach (SPINACIA OLERACEA L.)

“…However, it should be mentioned that the application of far-red light resulted in weak and thin leaves (data not shown). Inversely blue light inhibited the leaf expansion thus decreased the specific leaf area and increased the leaf thickness (it was observed, but not measured), similarly as was found at higher light intensity by us and by Meziane and Shipley (1999).…”

“…A relative overexcitation of PSII can results in an imbalance of photosynthetic electron transport between PS II and PS I, which can decrease the efficiency of the photosynthetic processes. In addition, the blue light-induced 'sun-type' characteristics of leaves was manifested also in the decrease of chlorophylls in spinach leaves, similarly as was found by Zhang et al (2016) and Monostori et al (2018). To ensure the optimal growth a fine balance between the blue and red ratio is necessary to provide equilibrated and efficient utilization of absorbed light energy between the PS II and PS I.…”

Breeding crops to feed 10 billion

“…Furthermore, the ratio of red to blue light is also important for flowering 70 , which, in wheat, is induced earliest under pink light, where the ratio is around 1 (ref. 71 ). One feature of existing speed breeding systems is the use of LEDs to improve light quality and reduce operational costs 12,15 .…”

Variations in aroma and specific flavor in strawberry under different colored light‐quality selective plastic film

“…In addition, R film was beneficial to the accumulation of soluble proteins, which was consistent with the results of R light increasing soluble protein content in Phaseolus vulgaris 43 and wheat. 44 Anthocyanins are responsible for red or purple coloration in a variety of fruits, are major pigments in strawberry, and are beneficial to human health as antioxidant agents. 29,45 Zhang et al 28 found that R light and RB light induced the strawberry coloration earlier by increasing the content of total anthocyanins.…”