A novel new light recipe significantly increases the growth and yield of sweet basil (Ocimum basilicum) grown in plant factory system

Abstract

Light is a crucial element for plant growth and production. High-pressure sodium (HPS) lamps are considered not very electrically efficient as they generate high radiant heat, and as a consequence, there has been a lot of interest in replacing HPS lamps with new more efficient lighting sources in the form of light-emitting diodes (LEDs). LEDs have a linear photon output with the electrical input current, and this great feature allows the design of lighting arrays that match the plant's needs. In the current study, light spectrum absorbance of pigments extracted from 14 plant species was analyzed. Two absorbance peaks were observed in the Photosynthetically Active Radiation (PAR) region: one at 435 nm and the other at 665 nm. The light spectrum array was designed to produce the spectrum absorbed by basil pigments. This included the use of new wavelengths of 435 ± 5 nm to cover the blue region. Moreover, the ratio between blue and red was considered to match the absorbance of basil pigment. The use of a light spectrum that matches the plant absorbance significantly improved the investigated physiological parameters and increased the growth yield of basil. Moreover, this is the first to confirm the great positive impact of using 435 nm light spectrum in comparison with the commercially widely used 450 nm LED spectrum. This investigation has great scientific and commercial applications in the field of indoor faming and plant factory systems.