EFFECT OF DIFFERENT LIGHT SPECTRA ON THE SEEDLING GROWTH OF LETTUCE (Lactuca sativa L.)

Abstract

ABSTRACT

In tropical regions like the Philippines, lettuce production requires optimized lighting, yet local data on the economic and physiological impacts of specific LED recipes remains scarce. This study aimed to evaluate how different LED spectral compositions influence the growth, morphological development, and financial viability of ‘Olmetie RZ’ lettuce seedlings. Using a Completely Randomized Design, four treatments were evaluated over 21 days: White Light, Red Light, Balanced Spectrum (50:50 Red-Blue), and Tri-color Full Spectrum.

Findings revealed that the Balanced Spectrum significantly outperformed all other treatments, yielding the highest fresh weight (2.91 g) and superior leaf morphology. Conversely, Red Light produced "leggy," less marketable growth. Economically, the Balanced Spectrum proved most efficient, yielding an 80% batch ROI and a 197% projected annualized ROI. The study concludes that a 50:50 Red-Blue ratio is the optimal "light recipe" for this variety. This project is significant for Philippine controlled environment agriculture, providing local growers with a scientifically-backed strategy to maximize seedling vigor and long-term financial sustainability through cost-effective, high-value lighting systems.

Keywords: Controlled Environment Agriculture, LED Spectra, Lettuce Seedlings, ROI, Olmetie RZ