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Chlorophyll Fluorescence as a Biological Feedback Signal for Optimized Plant Growth Conditions and Stress Diagnosis.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Chlorophyll Fluorescence as a Biological Feedback Signal for Optimized Plant Growth Conditions and Stress Diagnosis./
作者:	Ahlman, Linnea.
面頁冊數:	1 online resource (55 pages)
附註:	Source: Dissertations Abstracts International, Volume: 83-07, Section: B.
Contained By:	Dissertations Abstracts International83-07B.
標題:	Greenhouses. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28928930click for full text (PQDT)
ISBN:	9798762121323

Chlorophyll Fluorescence as a Biological Feedback Signal for Optimized Plant Growth Conditions and Stress Diagnosis.
Ahlman, Linnea.

Chlorophyll Fluorescence as a Biological Feedback Signal for Optimized Plant Growth Conditions and Stress Diagnosis. - 1 online resource (55 pages)

Source: Dissertations Abstracts International, Volume: 83-07, Section: B.

Thesis (Ph.D.)--Chalmers Tekniska Hogskola (Sweden), 2021.

Includes bibliographical references

The use of light emitting diodes (LEDs) instead of traditional high pressure sodium lamps, in greenhouses and indoor growing facilities, enables tuning and optimization of both light intensity and light spectrum. This opens for an energy saving potential not possible otherwise. Furthermore, such controllable lamps can be used to generate low intensity light excitations, which cause changes in the plants' chlorophyll fluorescence (ChlF). Analysis of these changes can then be used for plant diagnosis. We have conducted such experiments on plants to evaluate if and how proximal sensed ChlF, measured on canopy level, can be used as a biological feedback signal for spectrum optimization, stress detection, and for light intensity optimization.We found that steady-state ChlF have a strong correlation with short term photosynthesis and can be used for estimation of relative efficiency of different LED colors with respect to each other. We did not find significant changes in the relative efficiencies when light intensity or spectrum was changed, as was initially hypothesized. However, the method can still be applicable for spectrum calibration, as the efficiencies of different LED colors vary individually as the diodes degrade with time and they also vary to different degree depending on the operating temperature.Experiments on abiotically stressed plants (drought, salt, and heat) showed that variations in the dynamics of the ChlF signal can be used to classify plants as healthy or unhealthy. Experiments with the root infection Pythium ultimum indicated that severe infection is detectable. This is promising as it by its nature is hard to detect without harvesting. More research is needed though, to statistically verify if this, and other biotic stress factors can be detected, and if so, how severe the infection must be.Fast ChlF gain, defined as the amplitude of the ChlF signal caused by light pulses with a high frequency and a low intensity, was found to have a concave shape with respect to light intensity. Furthermore, the light intensity corresponding to the maximum of the fast ChlF gain coincide with the light level where the photosynthetic rate starts to saturate, which in some sense can be regarded as an optimal light level for efficient growth. Hence, we suggest the use of an extremum seeking controller to force the light intensity level to this point and demonstrates how this works in a simulation study.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798762121323Subjects--Topical Terms:

1530611
Greenhouses.
Index Terms--Genre/Form:

542853
Electronic books.

Chlorophyll Fluorescence as a Biological Feedback Signal for Optimized Plant Growth Conditions and Stress Diagnosis.
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100 1 $a Ahlman, Linnea. $3 3703240
245 1 0 $a Chlorophyll Fluorescence as a Biological Feedback Signal for Optimized Plant Growth Conditions and Stress Diagnosis.
264 0 $c 2021
300 $a 1 online resource (55 pages)
336 $a text $b txt $2 rdacontent
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500 $a Source: Dissertations Abstracts International, Volume: 83-07, Section: B.
500 $a Advisor: Wik, Torsten.
502 $a Thesis (Ph.D.)--Chalmers Tekniska Hogskola (Sweden), 2021.
504 $a Includes bibliographical references
520 $a The use of light emitting diodes (LEDs) instead of traditional high pressure sodium lamps, in greenhouses and indoor growing facilities, enables tuning and optimization of both light intensity and light spectrum. This opens for an energy saving potential not possible otherwise. Furthermore, such controllable lamps can be used to generate low intensity light excitations, which cause changes in the plants' chlorophyll fluorescence (ChlF). Analysis of these changes can then be used for plant diagnosis. We have conducted such experiments on plants to evaluate if and how proximal sensed ChlF, measured on canopy level, can be used as a biological feedback signal for spectrum optimization, stress detection, and for light intensity optimization.We found that steady-state ChlF have a strong correlation with short term photosynthesis and can be used for estimation of relative efficiency of different LED colors with respect to each other. We did not find significant changes in the relative efficiencies when light intensity or spectrum was changed, as was initially hypothesized. However, the method can still be applicable for spectrum calibration, as the efficiencies of different LED colors vary individually as the diodes degrade with time and they also vary to different degree depending on the operating temperature.Experiments on abiotically stressed plants (drought, salt, and heat) showed that variations in the dynamics of the ChlF signal can be used to classify plants as healthy or unhealthy. Experiments with the root infection Pythium ultimum indicated that severe infection is detectable. This is promising as it by its nature is hard to detect without harvesting. More research is needed though, to statistically verify if this, and other biotic stress factors can be detected, and if so, how severe the infection must be.Fast ChlF gain, defined as the amplitude of the ChlF signal caused by light pulses with a high frequency and a low intensity, was found to have a concave shape with respect to light intensity. Furthermore, the light intensity corresponding to the maximum of the fast ChlF gain coincide with the light level where the photosynthetic rate starts to saturate, which in some sense can be regarded as an optimal light level for efficient growth. Hence, we suggest the use of an extremum seeking controller to force the light intensity level to this point and demonstrates how this works in a simulation study.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
650 4 $a Greenhouses. $3 1530611
650 4 $a Farm buildings. $3 3688430
650 4 $a Flowers & plants. $3 3564028
650 4 $a Lighting. $3 808651
650 4 $a Photobiology. $3 610835
650 4 $a Carbohydrates. $3 522687
650 4 $a Adenosine triphosphate. $3 3331834
650 4 $a Optimization. $3 891104
650 4 $a Carbon dioxide. $3 587886
650 4 $a Weather. $3 523974
650 4 $a Photosynthesis. $3 518350
650 4 $a Light emitting diodes. $3 578763
650 4 $a Chloroplasts. $3 592562
650 4 $a Lamps. $3 3684689
650 4 $a Heat. $3 573595
650 4 $a Carotenoids. $3 662710
650 4 $a Energy. $3 876794
650 4 $a Urban areas. $3 3546012
650 4 $a Chlorophyll. $3 1004345
650 4 $a Agriculture. $3 518588
650 4 $a Agricultural engineering. $3 3168406
650 4 $a Horticulture. $3 555447
650 4 $a Electrical engineering. $3 649834
650 4 $a Plant sciences. $3 3173832
655 7 $a Electronic books. $2 lcsh $3 542853
690 $a 0791
690 $a 0473
690 $a 0471
690 $a 0544
690 $a 0479
690 $a 0539
710 2 $a ProQuest Information and Learning Co. $3 783688
710 2 $a Chalmers Tekniska Hogskola (Sweden). $3 1913472
773 0 $t Dissertations Abstracts International $g 83-07B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28928930 $z click for full text (PQDT)