Influence of controlled light condition on developmental parameters of tomato seedlings (Solanum lycopersicum)

Light emitting diodes (LED-lamps) used in plant production should emit radiation spectrum consisting of a selected wavelengths adjusted to the absorption spectrum of chlorophyll “a” and “b”. The aim of the study was to evaluate effect of supplementary lighting on seedlings of tomato cultivars 'Starbuck' F₁ and 'Komeett' F₁ in control conditions of growth chamber (phytotron). LED-lamps and high-pressure sodium (HPS) lamps had average light irradiation intensity 150-200 µmol m^-2 s^-1 at plant top. The effects on plant were determined by several physiological parameters such as chlorophyll content, photosynthesis and transpiration rate, stomatal conductivity and radiation. The results had shown that seedlings from mix LEDs had lowest stem elongation (6.8 cm) although the leaf area was increased (1172.83 cm²) which m ay be far more beneficial in seedling production. Collected data showed that selected wavelengths (particularly mixed LED light) positively affected photosynthesis process (3.25 µmol CO₂ m^-2 s^-1). However, the highest value of photosynthesis observed under HPS-lamps (3.52 µmol CO₂ m^-2 s^-1). Content of chlorophyll “a” increased in LEDs treatments (mix LEDs 2.94, blue LEDs 2.61 mg 100 g^-1 of dry weight) in comparison with HPS-lamps (1.59). Yield of tomato 'Komeett' was higher in treatment lighted by mix LEDs (8019 g m^-2) compared to HPS-lamps resulted in 6492.2 g m^-2.