This thesis describes how different colours of light affect various aspects of the growth and development of Arabidopsis and tomato plants. In the first chapter, we review the current knowledge of... Show moreThis thesis describes how different colours of light affect various aspects of the growth and development of Arabidopsis and tomato plants. In the first chapter, we review the current knowledge of light receptors and different light-regulated processes. In the second chapter we investigated the effect of direct illumination of roots. In the third chapter we presented an overview of the phenotypes that arise when plants are grown in white, red or blue light. In the fourth and fifth chapter we further investigate the stem and flowering phenotypes that were observed in the different light conditions. Altogether we show that red and blue light often act antagonistically, and that some light-regulated processes may be species- or age-specific. Show less
Spaninks, K.; Lamers, G.E.M.; Lieshout, J. van; Offringa, R. 2023
In vertical farming, plants are grown in multi-layered growth chambers supplied with energy-efficient LEDs that produce less heat and can thus be placed in close proximity to the plants. The... Show moreIn vertical farming, plants are grown in multi-layered growth chambers supplied with energy-efficient LEDs that produce less heat and can thus be placed in close proximity to the plants. The spectral quality control allowed by LED lighting potentially enables steering plant development toward desired phenotypes. However, this requires detailed knowledge on how light quality affects different developmental processes per plant species or even cultivar, and how well information from model plants translates to horticultural crops. Here we have grown the model dicot Arabidopsis thaliana (Arabidopsis) and the crop plant Solanum lycopersicum (tomato) under white or monochromatic red or blue LED conditions. In addition, seedlings were grown in vitro in either light-grown roots (LGR) or dark-grown roots (DGR) LED conditions. Our results present an overview of phenotypic traits that are sensitive to red or blue light, which may be used as a basis for application by tomato nurseries. Our comparative analysis showed that young tomato plants were remarkably indifferent to the LED conditions, with red and blue light effects on primary growth, but not on organ formation or flowering. In contrast, Arabidopsis appeared to be highly sensitive to light quality, as dramatic differences in shoot and root elongation, organ formation, and developmental phase transitions were observed between red, blue, and white LED conditions. Our results highlight once more that growth responses to environmental conditions can differ significantly between model and crop species. Understanding the molecular basis for this difference will be important for designing lighting systems tailored for specific crops. Show less
