Phenotyping 33 tomato genotypes grown under different LED light spectra.

MSc-thesis abstract (submitted 22 August 2016): There is an increasing interest in protected environment technologies such as LED lighting, which may contribute to increase horticulture yield and allow a year round production. The objective of this study was to characterize the effect of monochromatic blue LED (100% blue) lighting and UV-B radiation on several morphological and photosynthetic parameters of a wide variety of tomato genotypes.

Five tomato genotypes were chosen (per trait) based on their commercial relevance and contrasting morphological responses to three light treatments (Control or artificial sunlight - 100% Blue - Control no UV-B), where PPDF was 130 ┬▒ 20 ┬Ámol m-2 s-1.
Non-destructive and destructive measurements were conducted on 4 weeks old tomato plants.

As a general trend, plant height, leaf area and total dry weight were reduced when plants were exposed to monochromatic blue spectrum and to artificial sunlight (1h of UV-B radiation, 0.29 kJ m-2 d-1).
Stomatal conductance increased under the 100% blue treatment, though the level of significance varied among genotypes.
Leaf chlorophyll index increased under a UV-B containing environment, while there was no clear blue effect.
Leaf flavonol index increased under monochromatic blue and UV-B treatment.
Leaf anthocyanin index generally decreased as an effect of UV-B radiation and monochromatic blue spectra.

These findings will help us better understand how different genotypes of tomato plants respond under different LED lighting regimes and will lead to further experiments which will allow to breed for convenient morphological and photosynthetic characteristics.

Keywords: tomato, monochromatic blue, light emitting diodes (LEDs), UV-B, phenotyping.