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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
Question?