ENERGY EFFICIENCY OF LED LIGHT SOURCES WHEN PARSLEY FORCING

Abstract

Light-emitting diodes (LEDs) are a potential irradiation source for plant culture system due to ability to control the spectral composition in  red (R), green (G) and blue (B) bands of photosynthetically active radiation (PAR). To evaluate the energy efficiency of LEDs with different light quality in this study, we measured the growth and photomorfogenesis of root varieties of parsley (Petroselinum tuberosum). All plants were grown for 36 days at 50 mmol^.m^–2.s¹ photosynthetic photon flux with 8 hour photoperiod. The light quality of the flux was characterized by the ratio of the emission intensity of three spectral bands of PAR: , , . One part of the plants were grown under  the spectrum S1 closed to the equal dozes of the energy flow in the bands of PAR (=32,4 %,  =34,2 %, = 33,2 %).  The other part of the plants were grown under the spectrum S2 closed to the standart relative spectral efficiency of photosynthesis in a green plant leaf (=15,7 %, =9,8 %, =74,2 %). It was revealed that under the S1 spectrum the parsley had a stronger view, a greater number of leaves in the rosette, bigger  wet mass of leaves and dry matter content. An increasind in the overall length of the leaves of parsley plants grown under S2 spectrum occurs by the stem elongating while maintaining the proportions of the remainder part of the leaf. The energy consumption of the forcing under S1 spectrum was 12 % lower than under S2 spectrum. The obtained results allow us to conclude that recommended by some manufacturers the irradiation systems for plant culture, consisting only of a blue and red LEDs combination (with a higher proportion of red radiation) are not optimal for use when parsley forcing.