Study Examines Far-Red Light's Impact on Tomato Photosynthesis

Research from Ohio State University sheds light on how far-red photons affect light compensation point in tomato plants.

Published on Feb. 27, 2026

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A recent study from scientists at Ohio State University investigates the impact of far-red (FR; 701-750 nm) photons on leaf photosynthetic parameters in tomatoes. The research examines changes of light compensation point (LCP) with two definitions of photosynthetically active radiation (PAR: 400-700 nm; ePAR: 400-750 nm) under two FR-to-ePAR ratios (2% and 44%) for both acclimatization and light response curve measurement light sources. The findings highlight that different FR-to-ePAR ratios alter LCP as FR photons enhance photosynthesis in a synergetic manner with PAR photons.

Why it matters

Understanding how far-red light impacts photosynthesis in crops like tomatoes is crucial for optimizing lighting conditions in controlled environment agriculture, such as greenhouses and vertical farms. This research provides insights that can help growers better manage lighting to improve plant productivity and efficiency.

The details

The study examined changes in light compensation point (LCP), which is the light level at which photosynthesis equals respiration, under different ratios of far-red to photosynthetically active radiation (ePAR). The researchers found that higher levels of far-red light (44% FR-to-ePAR ratio) lowered the LCP compared to lower far-red levels (2% FR-to-ePAR ratio). This indicates that far-red photons can enhance photosynthesis in tomato plants when combined with PAR photons. The study also found that estimated LCP values differed depending on the definition of photosynthetically active radiation used (PAR vs. ePAR), highlighting the importance of including far-red photons for accurate LCP measurements.

  • The study was recently published in February 2026.

The players

Changhyeon Kim

Assistant professor at the University of Connecticut, formerly a postdoctoral scholar at Kubota lab at The Ohio State University. His research interests include understanding crop responses to varying environmental conditions, development of efficient management practices, and the application of new technology to maximize economic feasibility of Controlled Environment Agriculture.

Chieri Kubota

Distinguished Professor at The Ohio State University. Her projects are in an interdisciplinary area that encompasses plant physiology and horticultural engineering to enhance understanding and efficiency of CEA plant production systems such as greenhouses, warehouses (vertical farms), and growth chambers.

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What they’re saying

“These results indicate that inclusion of FR photons is essential for accurate estimation of LCP when the light environment of interest includes FR photons.”

— Changhyeon Kim, Assistant Professor (ASHS HortTech)

What’s next

The researchers plan to further investigate the synergistic effects of far-red and PAR photons on photosynthesis in tomato plants to develop more efficient lighting strategies for controlled environment agriculture.

The takeaway

This study highlights the importance of considering the full spectrum of light, including far-red photons, when optimizing lighting conditions for crop production in greenhouses, vertical farms, and other controlled environment agriculture systems.