Sequential RGB light optimization across developmental stages enhances lettuce growth through carry-over effects

Area of Science:

• Horticulture and Plant Science
• Controlled Environment Agriculture
• Plant Physiology

Background:

• Static light conditions in controlled environments may not align with plants' dynamic developmental needs.
• Optimizing light spectrum is crucial for maximizing plant growth and productivity.
• Understanding plant responses to varying light spectra is key for advanced cultivation.

Purpose of the Study:

• To develop and evaluate a stage-specific light optimization strategy for maximizing lettuce shoot fresh weight.
• To determine optimal red:green:blue (R:G:B) light ratios for early and late growth stages of lettuce.
• To compare the efficacy of sequential-optimized lighting against static and white LED treatments.

Main Methods:

• Lettuce growth period divided into early stage (ES) and late stage (LS).
• Response surface methodology used to identify optimal R:G:B light ratios for each stage.
• Sequential-optimized lighting strategy evaluated against static-optimized and white LED controls.

Main Results:

• Optimal R:G:B ratios determined as 44.2:55.8:0 for ES and 25.2:57.8:16.9 for LS.
• Excluding blue light in ES promoted favorable morphology for light interception, enhancing later biomass.
• Sequential-optimized lighting strategy yielded the greatest final biomass compared to all other treatments.

Conclusions:

• Dynamic, stage-specific light management significantly enhances crop productivity in controlled environments.
• Tailoring light spectra to developmental stages is critical for optimizing plant growth and yield.
• This study provides a framework for adaptive lighting strategies in commercial horticulture.