This study aimed to investigate the effects of various combinations of light-emitting diodes (LEDs) on the germination and growth of Indian spinach (Basella alba L.). For this purpose, we exposed plants to the following wavelengths of artificial light: only red (R10), only blue (B10), and combinations of red and blue light in the ratios 7:3 (R7B3), 5:5 (R5B5), and 3:7 (R3B7). Twenty days after sowing, the seed germination percentage was 81.3%, 72.5%, 63.8%, 58.8%, and 55.0% in plants exposed to R10, R7B3, R3B7, B10, and R5B5, respectively. Furthermore, plants exposed to R10 exhibited significantly higher germination energy, time to the first germination, and time required for 50% germination compared to those of plants exposed to the other LED combinations. After LED exposure, the growth analysis revealed that plant height and leaf length, width, and area were notably increased under R10 exposure. In contrast, plant height, leaf length, width, and area of plants irradiated with LED combinations emitting blue light were lower than those irradiated with R10. Nonetheless, Indian spinach cultivated under R10 conditions exhibited the lowest chlorophyll content compared to that of the other treatments. These findings suggest that red LEDs have a positive effect on seed germination and growth in Indian spinach. Therefore, the wavelength of LEDs must be selected depending on the aim of cultivation, especially for Indian spinach cultivated under an artificial light source, such as in a plant factory.
Keywords: medicinal crop, plant factories, germination rate, growth characteristics