Influence of the quality of artificial light on grafting tomato

To improve the success of grafted tomato plants, the response under different types of lighting has been evaluated. The lights used are compact fluorescent, high efficiency fluorescent, standard fluorescent and pure Blue-Light-Emitting Diodes. The assay was conducted in a culture chamber under the following conditions: temperature (night-day) 17.5/19.8 degreesC (0.8 +- 0.2/0.1 degreesC), relative humidity 56.44/72.40% (6.65 +- 0.01%) and radiation 92, 70, and 36 Wm-2. The tomato (Solanum lycopersicum L.) grafting method used was tube grafting with a small grafting clip using the cultivars Myla as scion and Maxifort as rootstock. Spectral radiation was measured at canopy level. Fresh and dry biomass in partitioning organs (leaves, stems and roots), Indol Acetic Acid (IAA), proline and reducing sugars were quantified. Standard fluorescent lamps have a very interesting spectral quality for grafting applications due to their B:R (blue:red), B:FR (blue:far red), PAR:NIR (Photosynthetically Active Radiation:Near Infrared) and R:FR (Red:Far Red) ratios; grafted plants under standard fluorescent lamps present lower proline concentrations (990mug per g of fresh weight) and higher sugar concentrations (27mug per g of fresh weight) than plants under other treatments. Furthermore, standard fluorescent lamps ensure the highest stem and root growth as well as an adequate water status.