Phenotyping 40 tomato genotypes grown under LED with different R:FR ratio

MSc-thesis abstract (submitted 25 July 2016): Tomato (Solanum lycopersicum L.) is an important vegetable crop that is daily consumed worldwide for its savor and nutritional properties. More than ten thousand species are listed and some cultivars are used as a reference to gain deeper knowledge in genomics. Growing tomato plants in protected environment allows year round production and higher yield per meter square. Light can be a limiting factor in some countries and investing in supplemental lighting is a necessity in order to provide quantity and quality fruits into the market.

Light emitting diodes (LED) were only used in the present study in order to phenotype 40 different tomato genotypes under climate controlled conditions. The photosynthetic active radiation intensity was set at a maximum of 150 µmol m-2 s-1 and minimum 100 µmol m-2 s-1 at plant height when starting the experiments. The aim was to collect morphological and physiological data of tomato genotypes grown under three different far-red light intensities (1, 26 and 65 µmol m-2 s- 1). Measurement such as chlorophyll fluorescence, chlorophyll index and stomatal conductance were done one week before the harvest.

After young plants spent three weeks in the climate chamber, destructive measurements took place to collect information about the total biomass accumulated, the stem and roots length, as well as leaf area. Plants under high far-red irradiance resulted in tallest plants with highest increase in hypocotyl and epicotyl length compare to the control and low far-red treatments. Similar trends were observed for the total biomass accumulated, stem and leaf dry weights, as well as anthocyanin index. Contrastingly, the chlorophyll index was decreased under the highest far-red irradiance. The yields of photosystem II from chlorophyll fluorescence measurements was found lower with plants grown under the high far-red irradiance.
The big data collection that was made will be useful for further experiments in greenhouses and will serve as a valuable tool to identify tomato traits for further breeding projects.

Keywords: tomato, 40 genotypes, light emitting diodes (LED), far-red light, shade avoidance syndrome, chlorophyll fluorescence, total biomass