Led spectral composition effects on mycorrhizal symbiosis formation with tomato plants

- Red, green and blue LEDs affected below- and aboveground tomato performance.
- White fluorescence stimulated soil enzyme activities and leaves' flavonoid synthesis.
- Red-blue LEDs increased inoculated tomatoes shoot biomass and photosynthesis.
- Red-green LEDs promoted mycorrhizal development and nitrogen metabolism.

The present study discusses physiological and biochemical nature of relationships between below- and aboveground processes affected by three different lights spectra. Our objective was to characterize the effect of light quality on Solanum lycopersicum L. by determination of the mycorrhizal function, soil enzyme activities and plant performance (growth, photosynthesis, secondary metabolites and the enzymes linking nitrogen and carbon metabolism). A growth chamber experiment was conducted with young tomato plants and the light was provided by fluorescent tubes (white light, WL) and computer controlled light system that combines four lamps with 4 cm2 arrays of red, green, blue, amber LEDs. The combinations were RB (Red 66%, Blue 33%) and RG (Red 66%, Green 33%). Under WL mycorrhizal fungi promoted soil fertility increasing enzyme activities and this was linked to the higher plant biomass accumulation. Also, we found the same upward trend between the values of root and soil alkaline phosphatase together with acid root phosphatase activity and accumulation of flavonoids in leaves. RB light stimulated shoot biomass production and gas-exchange parameters in inoculated tomatoes. The enhancement of soil urease activity, mycorrhizal development and nitrogen content in the leaves in parallel with nitrate reductase activity were as a consequence of RG lightening. Plant responses to the light quality and quantity precise manipulation and inoculation with beneficial soil microorganisms could be perspective in extending the production economic efficiency and nutrition potential of vegetables grown in controlled environments.