The effect of photosynthetic photon flux density on cucumber transplants growth indoors

Abstract

The light, quality and intensity of light are the key elements to optimize of high quality vegetable transplants. The objective of our studies was to evaluate the growth of cucumber (Cucumis sativus L. ‘Pasalimo F1’) transplants, cultivated under various photosynthetic photon flux densities (PPFD) were provided by light-emitting diodes (LEDs). Experiment was performed in phytotron complex of Institute of Horticulture, LCAFS. A system of high-power, solid-state lighting modules with 92% 638 nm (red) + 665 nm (red) + 731 nm (far red) and 8% 447 nm (blue) was used in the experiments. The generated PPFD of each type of five solid-state modules was - ~100, ~200, ~300, ~400, ~500 μmol m-2 s-1. Our experiment revealed that increased shoot and root fresh/dry weight dependet on increased PPFD. 400 μmol m-2 s-1 LED illumination had positive effect on shoot height, hypocotyl diameter and leaf number. Cucumbers which were grown under 100 μmol m-2 s-1 had longer hypocotyl than other modules, but their development has been slower as compared to other plants. 400 μmol m-2 s-1 LED illumination had positive effect on photosynthetic rate. It is determined that PPFD had no impact for content of photosynthetic pigments in leaves of all modules cucumber hybrid transplants.