Article

Minor Spectral Shifts Modulate Morphology, Stomatal Physiology and Nutrient Yield in Culinary Herbs under Controlled Environment Agriculture

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Abstract

Controlled environment agriculture (CEA) offers an unprecedented opportunity to tune light spectra for intentional enhanced growth and nutrient quality. In a 49-day experiment based on the NASA Growing Beyond Earth program, our hypothesis tested whether a slight increase in the blue and green fractions of light, an unintentional factor attributed to calibration error, would affect morphology, stomatal conductance, and estimated nutritional yield of three widely cultivated and medicated culinary herbs: Genovese Basil (Ocimum basilicum 'Genovese'), Cilantro (Coriandrum sativum 'Cilantro Cruiser'), and Chervil (Anthriscus cerefolium 'Vertissimo'). All plants were grown in five identically controlled environment chambers - four experimental chambers with slightly more blue (≈62.5 PPFD) and green (≈23.5 PPFD) photons and one control with a white light setting (≈121.1 PPFD green; ≈45.8 PPFD blue).

Plant height, width, and depth were measured over seven timepoints, and stomatal conductance (gsw) was measured for basil and cilantro (not chervil due to leaf sensitivity to structure). Gsw from leaves was taken as an average between the middle leaf and the two adjacent neighbors. Gsw was tested three times over the period (day 44 around 11:30 AM, day 46 and 49 around 15:30) to measure diurnal gsw patterns. Thus, after winsorisation of extreme outliers and averaging the two most trustworthy readings per leaf averaged per plant, it was determined that there are significant species-specific differences in experimental response. Genovese Basil showed modest reduction in height in the experimental spectral conditions but maintained constant values in canopy width and depth relative to the control. Cilantro experienced significant reductions across all three dimensions in experimental chambers, while chervil experienced a reduction in height but a relative increase in width across conditions in only one replicate. Morning stomatal conductance averaged 0.044–0.13 mol m⁻² s⁻¹ for basil and 0.13–0.28 mol m⁻² s⁻¹ for cilantro, exceeding afternoon values by 60–120 %. These values fell within the published ranges of reported values for both well-watered basil and cilantro under optimal conditions. Therefore, minor variations in the environment have the potential to incur significant changes in plant physiology. The modest spectral shift therefore influenced plant architecture and stomatal physiology in a species‑dependent manner, with potential implications for nutrient yield and water‑use efficiency. Our findings underscore the importance of routine spectral calibration in CEA systems and highlight the need to account for diurnal variation when interpreting physiological measurements.

Keywords: controlled environment agriculture, blue light, green light, stomatal conductance, Genovese basil, cilantro, chervil, medicinal herbs

How to Cite:

Chandalia, N. & Mekapati, J., (2025) “Minor Spectral Shifts Modulate Morphology, Stomatal Physiology and Nutrient Yield in Culinary Herbs under Controlled Environment Agriculture”, Journal of Medicinally Active Plants 14(4), 31–42. doi: https://doi.org/10.7275/jmap.3641