ARI Agricultural Research Institute Kromeriz Ltd.
Fluorescence imaging - a new tool for weed sensing?
Karel KLEM, Ladislav NEDBAL
ARI Agricultural Research Institute Kromeriz Ltd.
Bottlenecks of implementing site specific weed management
• Weed detection– labour intensive visual assessment– automatic weed detection (on-line or off-line)
• Decision support systems – economic thresholds (short term) or economic
optimum thresholds (long term) – adjusting of herbicide dose or long term
rationalisation of herbicide use
ARI Agricultural Research Institute Kromeriz Ltd.
Present state of automatic weed detection
• several methods are available1. reflectance masurements in NIR spectrum
• not species specific
• in narrow row crops difficult to distinguish between crop and weed
2. image analysis systems• the shapes of different plants overlap and vary
greatly because of different viewing angles in field conditions
ARI Agricultural Research Institute Kromeriz Ltd.
There is a possibility of improving weed detection using a new approach based on unique method of chlorophyll fluorescence imaging (PSI Brno, Czech Republic). Fluorescence kinetics is measured with this instrumentation for every pixel of the image.
Chlorophyll fluorescence imaging
ARI Agricultural Research Institute Kromeriz Ltd.
QA- QA
- QA- QA
- QA- QA
-
fluorescence
In fluorescence, the actinic light elicits in plants the Kautsky effect of
fluorescence induction.
from F0 with open PSII RC’s
to FPEAK with mostly closed PSII RC’s
ARI Agricultural Research Institute Kromeriz Ltd.
• 2 dimensional map of weed and crop plants distribution
• very strong discrimination between plants and background
• kinetics of fluorescence signal for each selected object
•species specific differencies in fluorescence kinetics (crop/ weed and weed/weed)
Results of fluorescence imaging
ARI Agricultural Research Institute Kromeriz Ltd.
• possibility to use different measurement protocols (wizard or own protocol)
ARI Agricultural Research Institute Kromeriz Ltd.
The objects for analysis can be selected manually.
Objects identification that will be analyzed as distinct entities with a characteristic fluorescence
emission
Alternatively the analysis can be done semi-automatically using either directly the fluorescence signal or its gradient.
Alternatively the analysis can be done semi-automatically using either directly the fluorescence signal or its gradient.
For a semi-automatic selection, the Low and High limits of the signal are defined and the areas conforming to these limits are colored in red.
ARI Agricultural Research Institute Kromeriz Ltd.
sergj
ARI Agricultural Research Institute Kromeriz Ltd.
Average fluorescence kinetics for winter wheat and selected weed species
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ARI Agricultural Research Institute Kromeriz Ltd.
Measurement of fast chlorophyll fluorescence iduction with portable PEA (Hansatech) instrument
• 2 s experiment• light adapted samples• computer based data
processing (software BIOLYZER)
• Output: fluorescence kinetics and photosynthetic parameters
ARI Agricultural Research Institute Kromeriz Ltd.
Variation in fluorescence kinetics (kautsky eff.) between 11 winter wheat varieties
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Fluorescence kinetics by 11 winter wheat varieties
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ARI Agricultural Research Institute Kromeriz Ltd.
Differences in fluorescence kinetics of Apera spica-venti in three different growth stages
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Differences in fluorescence kinetics of Apera spica-venti by different growth stages
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ARI Agricultural Research Institute Kromeriz Ltd.
Variation in fluorescence kinetics measured in two different growth stages of Sinapis alba
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Variation in fluorescence kinetics of Sinapis alba in cotyledons stage
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Variation in fluorescence kinetics of Sinapis alba in first pair of true leaves stage
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ARI Agricultural Research Institute Kromeriz Ltd.
Differences in fluorescence kinetics between winter wheat and Apera spica-venti plants (2 leaves)
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Differences in fluorescence kinetics between winter wheat and Apera spica-venti (2 leaves and more)
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ARI Agricultural Research Institute Kromeriz Ltd.
Differences in fluorescence kinetics between winter wheat and Matricaria perforata in two growth
stages
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Differences in fluorescence kinetics between winter wheat and Matricaria perforata (cotyledons)
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Differences in fluorescence kinetics between winter wheat and Matricaria perforata (true leaves)
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ARI Agricultural Research Institute Kromeriz Ltd.
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Amaranthus retroflexus
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Chenopodium album
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Sinapis alba
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Galium aparine
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ARI Agricultural Research Institute Kromeriz Ltd.
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Species-specific differences in photosynthetic parameters
ARI Agricultural Research Institute Kromeriz Ltd.
Pattern recognition
Neural network - most popular automatic discriminant method used in pattern recognition
fluorescence, photosynthetic or shape parameters
APESV TRIAE
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ARI Agricultural Research Institute Kromeriz Ltd.
Decision support systems
• Economic thresholds or adjusting of herbicide dose
• Need long-term evaluation of influence on:– weed population dynamics– economic output– total ammount of herbicide input into
environment
ARI Agricultural Research Institute Kromeriz Ltd.
Population dynamics of Galium aparine as influenced by decision system
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Starane 250 EC dose and efficacy0 1 2 3 4 5 60 l 0,4 l 0,4 l 0,4 l 0,4 l 0,4 l 0 lA - Economic threshold0% 100% 100% 100% 100% 100% 0%0 l 0,1 l 0,15 l 0,15 l 0,15 l 0,15 l 0,15 lB - Adjusting of herbicide
dose 0% 92% 98% 98% 98% 98% 98%
ARI Agricultural Research Institute Kromeriz Ltd.
Conclusion• Fluorescence imaging has a considerable
potential for improoving of automatic weed detection– species specific– undependent on viewing angle and leaf
overlappings
• This approach need extensive technical and experimental improovement and connection to decision support systém