Search

Remote sensing techniques are routinely used in plant species discrimination and of weed mapping. In the presented work, successful Silybum marianum detection and mapping using multilayer neural networks is demonstrated. A multispectral camera (green-red-near infrared) attached on a fixed wing unmanned aerial vehicle (UAV) was utilized for the acquisition of high-resolution images (0.1 m resolution). The Multilayer Perceptron with Automatic Relevance Determination (MLP-ARD) was used to identify the S. marianum among other vegetation, mostly Avena sterilis L. The three spectral bands of Red, Green, Near Infrared (NIR) and the texture layer resulting from local variance were used as input. The S. marianum identification rates using MLP-ARD reached an accuracy of 99.54%. The study had an one year duration, meaning that the results are specific, although the accuracy shows the interesting potential of S. marianum mapping with MLP-ARD on multispectral UAV imagery. [ABSTRACT FROM AUTHOR]

In the present study, the detection and mapping of Silybum marianum (L.) Gaertn. weed using novelty detection classifiers is reported. A multispectral camera (green-red-NIR) on board a fixed wing unmanned aerial vehicle (UAV) was employed for obtaining high-resolution images. Four novelty detection classifiers were used to identify S. marianum between other vegetation in a field. The classifiers were One Class Support Vector Machine (OC-SVM), One Class Self-Organizing Maps (OC-SOM), Autoencoders and One Class Principal Component Analysis (OC-PCA). As input features to the novelty detection classifiers, the three spectral bands and texture were used. The S. marianum identification accuracy using OC-SVM reached an overall accuracy of 96%. The results show the feasibility of effective S. marianum mapping by means of novelty detection classifiers acting on multispectral UAV imagery. [ABSTRACT FROM AUTHOR]

The effects of acetic acid fumigation, ethanol fumigation, and steam heat treatment on growth of Botrytis cinerea in vitro were investigated. The effect of steam heat treatments in combination with modified atmosphere packaging (MAP) on Botrytis decay development on ‘Hayward’ kiwifruit was also studied. The fungus was grown in Petri dishes on potato dextrose agar. Ethanol fumigation with 100 μl/l for 3 or 6 min, or 200 μl/l for 6 min enhanced the growth of B. cinerea. The effect of acetic acid on growth of B. cinerea was time and dosage-dependent. Fumigation with 1 μl/l for 6 min, 2 μl/l for 3 min, and 4 μl/l for 3 min promoted radial growth of the fungus when compared to the growth of the untreated control. Fumigation with 2 μl/l for 6 min delayed the growth of the fungus for the first 6 days, while fumigation with 6 μl/l for 3 min delayed the growth of the fungus after the sixth day. Fumigation with 4 or 6 μl/l acetic acid for 6 min, and 8 μl/l acetic acid for 3 or 6 min resulted in complete inhibition of fungal growth. Steam heat treatment at 45°C for 6 min, and at 48, 51, and 54°C for 3 or 6 min completely inhibited fungal growth in vitro. Furthermore, steam treatments at 47, 50, and 53°C for 3 or 6 min completely inhibited decay at the stem end of kiwifruit kept at 10°C in MAP for 12 days. However, none of the steam treatments inhibited decay in wounds on the surface of the fruit kept in MAP. [ABSTRACT FROM AUTHOR]