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 available 1. 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- QA-QA- QA-QA- QA-QA- fluorescence In fluorescence, the actinic light elicits in plants the Kautsky effect of fluorescence induction. from F 0 with open PSII RC’s to F PEAK 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. 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

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

ARI Agricultural Research Institute Kromeriz Ltd. Differences in fluorescence kinetics of Apera spica- venti in three different growth stages

ARI Agricultural Research Institute Kromeriz Ltd. Variation in fluorescence kinetics measured in two different growth stages of Sinapis alba

ARI Agricultural Research Institute Kromeriz Ltd. Differences in fluorescence kinetics between winter wheat and Apera spica-venti plants (2 leaves)

ARI Agricultural Research Institute Kromeriz Ltd. Differences in fluorescence kinetics between winter wheat and Matricaria perforata in two growth stages

ARI Agricultural Research Institute Kromeriz Ltd.

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 X1 X2 X3 X4

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

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