www.usask.ca

Determining drought stress resistance mechanisms in potato plants using GIS

Pankaj Banik, Winston Zeng, Helen Tai and Karen Tanino

www.usask.ca

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

www.usask.ca

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

www.usask.ca

Method 1: Hand section from fresh leaf

tedious job

interfering fluorescence

www.usask.ca

Method 2: Leaf imprint using Suzuki Universal Microprinting (SUMP) method

www.usask.ca

Platelets are broken

Imaginary gap among platelets

Method 2.1: Examining SUMP imprints using 3D confocal microscopy

www.usask.ca

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

www.usask.ca

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.

www.usask.ca

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”

www.usask.ca

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

www.usask.ca

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

www.usask.ca

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 .

www.usask.ca

Future Work with platelets

Remove noise of image (edges of the cell)

www.usask.ca

Drought stress mechanism: II. stem as a water reservoir

Cross-section

Stem

Water storage vessel Water transport vessel (store water during

drought stress)

Interest:

www.usask.ca

Measuring only the water transpiring vessels did not produce enough information

www.usask.ca

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

www.usask.ca

Acknowledgements

SAGES for funding the project

Spatial Initiative at USASK for providing a bursary for spatial measurements

Ting Wei for spatial work

www.usask.ca

Thank you

Question?