THE EFFECT OF PHOTOSYNTHETIC PHOTON FLUX DENSITY ON CUCUMBER AND TOMATO TRANSPLANTS ASSIMILATIVE INDICES

Abstract

The objective of our studies was to evaluate the assimilative indices of cucumber (‘Pasalimo F1’) and tomato (‘Marissa 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, LRCAF. 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 ~200 and ~400 μmol m^-2 s^-1. Our experiment revealed that increased net assimilation rate (NAR) depended on increased PPFD of cucumber and tomato hybrid. 400 μmol m^-2 s^-1 LED illumination had positive effect on relative growth rate (RGR). Cucumbers which were grown under 200 μmol m^-2 s^-1 had bigger leaf area ratio (LAR) and specific leaf area (SLA), their development has been bigger as compared to higher 400 μmol m^-2 s^-1 PPFD. High PPFD LED illumination had positive effect on leaf weight ratio (LWR), shoot root ratio (SRR) and tomato transplants development. These studies with various photosynthetic photon flux densities (PPFD) and LEDs light should be continued throughout plant vegetation.

 Keywords: assimilative indices, blue light, cucumber, PPFD, red light, tomato, transplants.

Article DOI: http://doi.org/10.15544/RD.2015.030