LED spectrum optimisation using steady-state fluorescence gains

Ahlman, Linnéa; Bånkestad, Daniel; Wik, Torsten

doi:10.17660/actahortic.2016.1134.48

Cited by 3 publications

(3 citation statements)

References 11 publications

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“…We have previously shown correlation with photosynthesis [26][27][28] and used it for growth tracking [29] and for light stress detection [30][31][32]. In the latter work, the variations in the DFR originating from a weak excitation from a blue LED light were used for light stress detection.…”

Section: Introductionmentioning

confidence: 99%

Stress Detection Using Proximal Sensing of Chlorophyll Fluorescence on the Canopy Level

et al. 2021

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Chlorophyll fluorescence is interesting for phenotyping applications as it is rich in biological information and can be measured remotely and non-destructively. There are several techniques for measuring and analysing this signal. However, the standard methods use rather extreme conditions, e.g., saturating light and dark adaption, which are difficult to accommodate in the field or in a greenhouse and, hence, limit their use for high-throughput phenotyping. In this article, we use a different approach, extracting plant health information from the dynamics of the chlorophyll fluorescence induced by a weak light excitation and no dark adaption, to classify plants as healthy or unhealthy. To evaluate the method, we scanned over a number of species (lettuce, lemon balm, tomato, basil, and strawberries) exposed to either abiotic stress (drought and salt) or biotic stress factors (root infection using Pythium ultimum and leaf infection using Powdery mildew Podosphaera aphanis). Our conclusions are that, for abiotic stress, the proposed method was very successful, while, for powdery mildew, a method with spatial resolution would be desirable due to the nature of the infection, i.e., point-wise spread. Pythium infection on the roots is not visually detectable in the same way as powdery mildew; however, it affects the whole plant, making the method an interesting option for Pythium detection. However, further research is necessary to determine the limit of infection needed to detect the stress with the proposed method.

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Section: Introductionmentioning

confidence: 99%

Stress Detection Using Proximal Sensing of Chlorophyll Fluorescence on the Canopy Level

et al. 2021

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“…We define the steady-state chlorophyll a fluorescence gain (dF740/dq) as the difference in fluorescence at 740 nm divided by the difference in incident light quanta caused by (a small) excitation of one LED colour. This work is an expansion of earlier research [16,17], where we proposed the use of the fluorescence gain as an measure of the photosynthetic efficiency increase, to be used as a feedback signal in a (future) self-optimising controller to find the optimal light spectrum.…”

Section: Introductionmentioning

confidence: 99%

“…In previous experiments we compared the fluorescence gains caused by an excitation of six different LED colours (in the absence of background light), for six different plant species [17], including basil, cucumber, and lettuce. Differences in the mutual relation of the fluorescence gains (caused by the different LED colours) were noticed between different plant species.…”

Section: Introductionmentioning

confidence: 99%

Relation between Changes in Photosynthetic Rate and Changes in Canopy Level Chlorophyll Fluorescence Generated by Light Excitation of Different Led Colours in Various Background Light

2019

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Using light emitting diodes (LEDs) for greenhouse illumination enables the use of automatic control, since both light quality and quantity can be tuned. Potential candidate signals when using biological feedback for light optimisation are steady-state chlorophyll a fluorescence gains at 740 nm, defined as the difference in steady-state fluorescence at 740 nm divided by the difference in incident light quanta caused by (a small) excitation of different LED colours. In this study, experiments were conducted under various background light (quality and quantity) to evaluate if these fluorescence gains change relative to each other. The light regimes investigated were intensities in the range 160-1000 µmol m −2 s −1 , and a spectral distribution ranging from 50% to 100% red light. No significant changes in the mutual relation of the fluorescence gains for the investigated LED colours (400, 420, 450, 530, 630 and 660 nm), could be observed when the background light quality was changed. However, changes were noticed as function of light quantity. When passing the photosynthesis saturate intensity level, no further changes in the mutual fluorescence gains could be observed.

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Usefulness of Broad-Spectrum White LEDs to Envision Future Plant Factory

Nozue

Gomi

2018

Smart Plant Factory

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LED spectrum optimisation using steady-state fluorescence gains

Cited by 3 publications

References 11 publications

Stress Detection Using Proximal Sensing of Chlorophyll Fluorescence on the Canopy Level

Stress Detection Using Proximal Sensing of Chlorophyll Fluorescence on the Canopy Level

Relation between Changes in Photosynthetic Rate and Changes in Canopy Level Chlorophyll Fluorescence Generated by Light Excitation of Different Led Colours in Various Background Light

Usefulness of Broad-Spectrum White LEDs to Envision Future Plant Factory

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