Photosynthetic Adjustments Maintain Lettuce Growth Under Dynamically Changing Lighting in Controlled Indoor Farming...

Area of Science:

• Controlled Environment Agriculture
• Plant Physiology
• Horticultural Lighting

Background:

• Plant acclimation to fluctuating light is well-understood.
• Dynamic lighting strategies in controlled environment agriculture (CEA) are underexplored.
• Alternating light intensity can mirror electricity prices, offering cost savings.

Purpose of the Study:

• To investigate the effects of dynamic lighting on lettuce physiology and metabolism.
• To assess the scalability of dynamic lighting strategies in different CEA setups.
• To determine if dynamic lighting impacts lettuce yield and quality.

Main Methods:

• Lettuce (Lactuca sativa L.) cv. "Katusa" was grown under dynamic lighting with uniform daily light integrals.
• Photosynthetic parameters, metabolic responses, and growth were recorded across three scales: phenotyping facility, testbed vertical farm, and commercial-scale vertical farm.
• Simulated commercial production evaluated saleable yield under constant and dynamic lighting, including split-night regimes.

Main Results:

• Lettuce plants effectively adjusted photosynthetic light reactions and carbon metabolism to dynamic light conditions.
• No significant changes in the overall metabolic composition of lettuce leaves were observed.
• Constant and dynamic lighting regimes produced comparable saleable lettuce head weights (87-89g) in a commercial-scale simulation.
• Split-night lighting regimes did not negatively impact yield.

Conclusions:

• Dynamic lighting is a viable strategy for indoor cultivation, enabling cost-effective production through optimized electricity use.
• Lettuce exhibits robust physiological acclimation to dynamic light, maintaining yield and quality.
• Dynamic lighting presents a promising approach for sustainable and economical CEA.