The effect of light emitting diode (LED) spectrum and light duration on growth and yield of Brassica sinensis L. grown on floating raft hydroponic system

Abstract

Recent technology in agriculture allows vegetable cultivation in controlled environment by utilizing energy derived from an artificial lighting. Light Emitting Diodes (LED) is a source of artificial light which produce light with the wavelength ranged from ultraviolet - 100 nm to infrared - 3,000 nm. Under natural or artificial lighting condition, plants require energy for photosynthesis from light between 380 nm to 700 nm. In this study we examined the use of two types of 45-watt LED (red and blue – C1, full spectrum – C2) with three different light durations (12 h – D1, 16 h – D2, and 18 h – D3) on the growth and yield performance of brassica under hydroponic technique. Research result showed that full spectrum LED provided better performance in plant height, leaves number and width, fresh yield, root length, and biomass in all combinations with light duration as compared to red and blue LED. The combination of full spectrum LEDs with a duration of 16 h showed the best fresh yield (3.96 kg m-2) followed by 18 h (3.57 kg m-2) and 12 h (3.22 kg m-2). Although the highest production was resulted from the combination of full spectrum LED and 16 h light duration, the most efficient in electric energy utilization was showed in the combination of full spectrum LED and 12 h light duration. All in all, we concluded that the use of full spectrum LED in combination with 16 h light duration feasible to be implemented in brassica cultivation under controlled environment.