7 research outputs found
Model-based scenario analysis for effective site-specific weed control on grassland sites
The site-specific management of weeds in grassland is often challenging
because different weed control strategies have different trade-offs regarding
the required resources and treatment efficiency. So, the question arises
whether a wide tractor-based system with section control or a small
agricultural robot has a higher weed control performance for a given
infestation scenario. For example, a small autonomous robot moving from one
weed to the next might have much shorter travel distances (and thus lower
energy and time costs) than a tractor-mounted system if the locations of the
weeds are relatively isolated across the field. However, if the plants are
highly concentrated in small areas so-called clusters, the increased width of
the tractor-mounted implement could be beneficial because of shorter travel
distances and greater working width.
An additional challenge is the fact that there is no complete knowledge of
the weed locations. Weeds may not have been detected, for example, due to their
growth stage, occlusion by other objects, or misclassification. Weed control
strategies must therefore also be evaluated with regard to this issue. Thus, in
addition to the driving distance, other metrics are also of interest, such as
the number of plants that were actually controlled or the size of the total
treatment area.
We performed this investigation for the treatment of the toxic Colchicum
autumnale, which had been detected in drone images of extensive grassland
sites. In addition to real data, we generated and analyzed simulated weed
locations using mathematical models of stochastic geometry. These offer the
possibility to simulate very different spatial distributions of toxic plant
locations. Different treatment strategies were then virtually tested on this
data using Monte Carlo simulations and their performance was statistically
evaluated.Comment: 20 pages, 9 figure
Phosphorylation Alters the Interaction of the Arabidopsis Phosphotransfer Protein AHP1 with Its Sensor Kinase ETR1
The ethylene receptor ethylene response 1 (ETR1) and the Arabidopsis histidine-containing phosphotransfer protein 1 (AHP1) form a tight complex in vitro. According to our current model ETR1 and AHP1 together with a response regulator form a phosphorelay system controlling the gene expression response to the plant hormone ethylene, similar to the two-component signaling in bacteria. The model implies that ETR1 functions as a sensor kinase and is autophosphorylated in the absence of ethylene. The phosphoryl group is then transferred onto a histidine at the canonical phosphorylation site in AHP1. For phosphoryl group transfer both binding partners need to form a tight complex. After ethylene binding the receptor is switched to the non-phosphorylated state. This switch is accompanied by a conformational change that decreases the affinity to the phosphorylated AHP1. To test this model we used fluorescence polarization and examined how the phosphorylation status of the proteins affects formation of the suggested ETR1âAHP1 signaling complex. We have employed various mutants of ETR1 and AHP1 mimicking permanent phosphorylation or preventing phosphorylation, respectively. Our results show that phosphorylation plays an important role in complex formation as affinity is dramatically reduced when the signaling partners are either both in their non-phosphorylated form or both in their phosphorylated form. On the other hand, affinity is greatly enhanced when either protein is in the phosphorylated state and the corresponding partner in its non-phosphorylated form. Our results indicate that interaction of ETR1 and AHP1 requires that ETR1 is a dimer, as in its functional state as receptor in planta
KleinrĂ€umig arbeitende Werkzeuge zur nicht-chemischen ZurĂŒckdrĂ€ngung von Herbstzeitlosen (Colchicum autumnale)
Um Herbstzeitlosen selektiv nicht-chemisch zurĂŒckdrĂ€ngen zu können, wurden verschiedene Werkzeuge in einer Nutzwertanalyse bewertet und in Feldversuchen untersucht. Der Pflanzenbestand konnte auf 0 bis 2 Pflanzen pro Quadratmeter bzw. in 3 Jahren auf 50% bis 68% reduziert werden
Detection of Colchicum autumnale in drone images, using a machine-learning approach
Colchicum autumnale are toxic autumn-blooming flowering plants, which often grow on extensive meadows and pastures. Thus, they pose a threat to farm animals especially in hay and silage. Intensive grassland management or the use of herbicides could reduce these weeds but environment protection requirements often prohibit these measures. For this reason, a non-chemical site- or plant-specific weed control is sought, which aims only at a small area around the C. autumnale and with low impact on the surrounding flora and fauna. For this purpose, however, the exact locations of the plants must be known. In the present paper, a procedure to locate blooming C. autumnale in high-resolution drone images in the visible light range is presented. This approach relies on convolutional neural networks to detect the flower positions. The training data, which is based on hand-labeled images, is further enhanced through image augmentation. The quality of the detection was evaluated in particular for grassland sites which were not included in the training to get an estimate for how well the detector works on previously unseen sites. In this case, 88.6% of the flowers in the test dataset were detected, which makes it suitable, e.g., for applications where the training is performed by the manufacturer of an automatic treatment tool and where the practitioners apply it to their previously unseen grassland sites