Low-cost spectrometers light the way for plant monitoring

Budget-friendly instruments prove reliable for measuring solar-induced chlorophyll fluorescence and tracking crop growth

Jiangsu, China -- Looking for the red glow from a leaf doesn’t have to put you in the red.

Nanjing University researchers have confirmed the efficiency of budget-friendly low-configuration spectrometers in retrieving solar-induced chlorophyll fluorescence (SIF) ­— the red glow that plants emit during photosynthesis and a critical marker of plant health and productivity. This research serves to democratize ecosystem and agricultural monitoring by leveraging cost-effective technologies.

The study was published in the Journal of Remote Sensing on Dec. 18.

Plants use most but not all of the sunlight they absorb for photosynthesis; some excess energy is released as heat and a red glow, known as SIF. This direct and non-invasive indicator offers unique insights into ecosystem health, productivity and responses to environmental changes.

Retrieving SIF, however, is neither simple nor cheap. It often involves high-configuration spectrometers that, though precise, are expensive and difficult to maintain, thereby limiting their deployment in the field.  

“Our goal was to determine whether low-configuration spectrometers could serve as viable tools for ground-based SIF observations,” said Lei Pei, a researcher at Nanjing University’s International Institute for Earth System Sciences and lead author of this study.

To make that determination, the team compared the performance of a high-end spectrometer with a more economical model at two agricultural sites growing wheat and rice in China. They assessed how well the spectrometers measured SIF, tracked crop productivity (gross primary productivity, or GPP), and identified key growth stages.

“We found that while there are differences in the magnitude of SIF values retrieved, both spectrometer types exhibited similar trends and sensitivities,” Pei said.

The low-configuration spectrometer closely matched the performance of the high-configuration spectrometer, with correlations exceeding 90% and minimal errors. It was particularly effective for wheat, accurately tracking plant productivity and growth stages with only a 2.5-day average difference in timing compared to the pricier model.

“This finding suggests that low-configuration spectrometers can fulfill certain requirements for field-based SIF observations, marking a significant step forward in advancing ground-based SIF research,” Pei said.

These findings support the establishment of more efficient and cost-effective field observation systems, rendering ecosystem and agricultural monitoring more accessible and scalable.

The researchers plan to further refine the accuracy of SIF retrievals from low-configuration spectrometers by examining additional factors that could impact their performance.

“Our ultimate goal is to develop a comprehensive framework that demonstrates the reliability of these instruments in supporting in situ SIF observation missions, thereby broadening access to this important area of research,” Pei said.

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References

DOI

10.34133/remotesensing.0369

Original Source URL

https://spj.science.org/doi/10.34133/remotesensing.0369

Funding information

• National Natural Science Foundation of China (42125105),
• National Key Research and Development Program of China (2022YFF1301900),
• Nanjing University Integrated Research Platform of the Ministry of Education - Top Talents Program (090414380033).

About Journal of Remote Sensing

The Journal of Remote Sensing, an online-only Open Access journal published in association with AIR-CAS, promotes the theory, science, and technology of remote sensing, as well as interdisciplinary research within earth and information science.