Effects of LED supplementary lighting regimes with different wavelengths on tomato seedling quality

This study aimed to develop low-cost lighting regimes to enhance the quality of tomato seedlings. Researchers investigated the effects of blue (B), red (R), and white (W) LEDs using three supplementary methods: discontinuous supplemental lighting (DSL), which activates when intensity is low; continuous lighting from sunrise to sunset (SLSS); and an extended photoperiod (SLP) of six hours. These were compared against natural daylight (C) and paclobutrazol (PC) application.Results indicated that while the PC treatment produced the shortest seedlings, it significantly reduced overall quality and extended the time required to reach planting size. In contrast, the DSL-W (discontinuous white light) treatment proved most effective for promoting root development. Although the SLSS treatment helped control seedling height, it negatively impacted leaf color and general quality. The SLP-R (extended red light) treatment yielded the most positive results, including the desired leaf color, the largest stem diameter, and the highest dry weights and growth rates. Consequently, while the tested light regimes did not serve as a complete alternative to PC for height control, red wavelengths and extended photoperiods significantly improved seedling quality. Ultimately, the DSL-W application was identified as a cost-effective alternative that provides satisfactory quality for tomato seedling production