Stomatal density is calculated by determining the number of stomata within a known area on a leaf's surface, typically using a microscope. Here's a step-by-step guide:
Steps to Calculate Stomatal Density
-
Calculate the Radius of the Field of View: This involves determining the radius of the circular area you are viewing through the microscope. The radius is half the diameter. You can use a stage micrometer to calibrate your microscope and accurately measure the diameter of the field of view at a specific magnification.
-
Calculate the Area of the Field of View: The area of the circular field of view is calculated using the formula for the area of a circle:
- Area = πr², where 'π' (pi) is approximately 3.14159, and 'r' is the radius of the field of view.
-
Count Stomata and Determine the Mean:
- Choose several fields of view: Select multiple, representative areas on the leaf sample under the microscope. Using multiple fields of view will give you a more accurate density estimate.
- Count the number of stomata in each field of view.
- Calculate the mean number of stomata per field of view by summing the number of stomata from each field of view and dividing by the number of fields of view counted. For example, if you counted 10, 12, and 14 stomata in three different fields of view, the mean would be (10 + 12 + 14) / 3 = 12 stomata.
-
Calculate Stomatal Density: Divide the mean number of stomata per field of view by the area of the field of view.
-
Stomatal Density = (Mean Number of Stomata) / (Area of Field of View)
-
This will give you the number of stomata per unit area (e.g., stomata per mm²).
-
-
Round to the Required Precision: Round the calculated stomatal density to the degree of precision needed (e.g., the nearest whole number, one decimal place, etc.).
Example
Let's say:
- The radius of your field of view is 0.5 mm.
- The area of your field of view is π * (0.5 mm)² ≈ 0.785 mm².
- The mean number of stomata per field of view is 15.
Then, the stomatal density would be:
- Stomatal Density = 15 stomata / 0.785 mm² ≈ 19.1 stomata/mm².
- Rounded to the nearest whole number, the stomatal density is approximately 19 stomata/mm².
