Efficiency of an alternative LED-based grow light system

Abstract

This article is dedicated to the assessment of the usage influence of LED lights of varying color spectrum on plant growth and development, and determining their usage impact. The research interest is focused on the usage of LED-based light system inside greenhouses for optimization of lighting conditions.Research methods. The current research focused on the following Green-LP™ LED-based grow lights: GLP-FH-56-B (30/70 % red(660 nm)/blue(445 nm) spectral composition), GLP-FH-56-R (70/30 % red/blue spectral composition) and GLP-FH-56-RB (50/50 % red/blue spectral composition). Examination of the influence of plant lamps on the growth processes was carried out at the laboratory conditions (23 °C during the day and 20 °C at night, humidity from 75 % to 80%, with the varying PAR intensity and the daylight of 16 h (supplementary illumination was provided for 6 to 8 hours)) with lettuce as a subject. Phenological observations and biometric registrations were conducted according to generally accepted techniques. Chlorophyll content was measured using the express method with atLEAF+ device. Results. Based on the results of the conducted experiments the highest germination rate was observed under the lamps with blue and blue-red spectral peaks, salad seedlings had largest shoot fresh weight under grow lights with red and blue-red spectrum peaks (0.235 and 0.250 g, respectively). The shoot weight exceeded that of control group of plants 1.8 to 2.1 times. Additionally, plants grown under the lamp with a blue spectral peak had 17 to 29 % more powerful root system than those grown under red one and 43 to 73 % higher than control group. Highest chlorophyll content was observed in plants grown under the lamps with blue spectral peak (440-450 nm), which exceeded by two times that in plants grown without supplementary illumination and was 1.8 times higher than that of plants grown under a high-pressure sodium arc lamp.Conclusion. LED lamps with different illumination spectrum can serve as an additional light source for plants grown inside greenhouses, positively affecting both growth and development of plants, and economical efficiency.