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Determining drought stress resistance mechanisms in potato plants using GIS
Pankaj Banik, Winston Zeng, Helen Tai and Karen Tanino
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Background
Potato is the 3rd most important food crop in the world
Good source of carbohydrate and vitamins
Potato plants are sensitive to drought stress
Drought stress affect tuber yield and quality
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Leaf cuticle layer prevents water loss from leaf surface during drought stress
Interest:
- Area
- Thickness
Drought stress resistance mechanism : I. Leaf cuticle layer prevents water loss
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Method 1: Hand section from fresh leaf
tedious job
interfering fluorescence
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Method 2: Leaf imprint using Suzuki Universal Microprinting (SUMP) method
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Platelets are broken
Imaginary gap among platelets
Method 2.1: Examining SUMP imprints using 3D confocal microscopy
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Method 2.2: GIS in this project
Software ArcGIS 10.2 (free license at U of S)
Part 1: Digitizing • Georefence images
• Digitize cell polygons
• Calculate area of the cell polygons in µm2
• Export area from ArcGIS to excel for statistics
Part 2: Elevation Modeling • Reclassify into 9 classes
• Export area from ArcGIS to excel
• Calculate the area of each class in each image
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Digitizing and Area Calculation
ArcGIS automatically calculate the area once you have created the polygon.
All polygons could be extracted by the customized tool as well.
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Elevation Modeling Challenge Lack of z value
information in the original image
Solution Treat brightness (value
of each pixel from the original image) as alternative measure of elevation
We assume that “the brighter, the higher”
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Elevation Modeling Original values
reclassified into 9 classes (classification methods: Natural Breaks)
Middle classes (3, 4 and 5) - 60% of area for most images
Elevation
High Low
Legend
Value
9
8
7
6
5
4
3
2
1
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Elevation Modeling Natural Breaks Classification
group similar values
maximize the differences
Old Values New Values
0 - 48 1
48 - 71 2
71 - 89 3
89 - 104 4
104 - 118 5
118 - 132 6
132 - 150 7
150 - 179 8
179 - 255 9
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Elevation Modeling ArcGIS automatically calculate the number of pixels (pixel size: 0.96 *0.96 µm2 ) in each class, and then we calculate the area of each class in µm2 .
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Future Work with platelets
Remove noise of image (edges of the cell)
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Drought stress mechanism: II. stem as a water reservoir
Cross-section
Stem
Water storage vessel Water transport vessel (store water during
drought stress)
Interest:
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Measuring only the water transpiring vessels did not produce enough information
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Total water storage area (red & green) and water transpiring area (yellow) can be measured by GIS to see if stem stores water during drought stress
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Acknowledgements
SAGES for funding the project
Spatial Initiative at USASK for providing a bursary for spatial measurements
Ting Wei for spatial work
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Thank you
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