Best Drought Resistant Plant Program (BDRP):

Methods Outline for Evaluating Drought Resistance

      For the BDRP Program, the best drought resistant plant is defined as the growing plant or plants that gain the most mass while consuming the least volume of nutrient solution. The following steps are an outline for collecting, recording, and converting measured data into a graph suitable for plant evaluation.

The Measured Data Table-

This data table is used to record plant data at the time of data collection. The headers for the table are shown below (N.S. = Nutrient Solution). Go to the Measured Data Table link for a copy of this table.

See the ‘Interactive Data Exercise’ link for practice on entering measured data, writing equations for and calculating N.S. usage values from the measured N.S. level values.

These values are recorded only once during the study.      The ‘Plant Number’ assures only that the correct data is used for the correct plant. The ‘Start Date’ is not used in the BDRP study. This value is used in ‘Best Plant Growth’ and ‘Best Overall Plant’ studies. The ‘Initial N.S. Level’ is used to convert all nutrient solution heights to nutrient solution usage. The ‘Plant Mass Final Day’ is used only if the investigator is reporting the results in ‘Edible Plant Mass’ instead of ‘Total Plant Mass’. Either mass reporting method gives the same result in the BDRP program.

Plant	Start	Initial N.S.	Plant Mass
Number	Date	Level (cm)	Final Day (g)

These values are recorded on each measurement date. ‘Date of Measurement’ values are not used in the BDRP program. These values are used in ‘Best Plant Growth’ and ‘Best Overall Plant’ studies. The ‘Measurement Number’ is used only as a guide for data entry. The ‘N.S. Level’ and the ‘Total Plant Mass’ values are entered in the ‘Measured Data Table and used in the construction of subsequent tables. The table will contain as many rows as the number of measurements made in the study. 

Date of	Measurement	N.S. Level	Total
Measurement	Number	(cm)	Plant Mass (g)

 

The Results Data Table-

      These values are recorded after the ‘Measured Data Table’ is complete. The ‘Measurement Number’ is used only as a guide for data entry. The ‘Total Plant Mass’ and the ‘Total Volume of N.S. Used’ values are used to create the scatter plot in the next step. The table will contain as many rows as the number of measurements made in the study. 

 

Measurement	Total	Total Volume
Number	Plant Mass (g)	N.S. Used (L)

The investigator will use the information from this table to create the ‘Plant Growth Scatter Plot’ graph described in the next step.

Creating ‘Plant Growth Scatter Plot’ Graph-

      After the results table is completed, the investigator is now ready to make a scatter plot with the plant mass and N.S. usage data pairs. The investigator can either follow the directions described in the ‘Scatter Plot Line Graph’ document or choose an interactive graph from the ‘Interactive Graph’ link. If an interactive graph is preferred, select a blank scatter plot graph from the link. Make sure the blank graph accepts the same number of data pairs as the number of measurements in the study.

      Once the blank graph is chosen, enter the data from the ‘Results Data Graph’ into the interactive graph data grid. The ‘Measure Number’ is not used, the ‘Total Plant Mass’ values go in the left column and the ‘Total M.S. Used values go in the right column. The graph will generate a scatter plot of these data pairs and form a ‘best straight line’ through the points. The graph will show the slope value for the line, and a statistical value for how well the points form a straight line. The investigator will record the line slope is the growth value used in the final ‘Summary Graph’. Use the example ‘Results Data Table’ below for practice with the interactive blank

Creating the ‘Best Drought Resistant Plant Summary’ Graph-

The investigator can either follow the directions described in the ‘Summary Bar Graph’ document or choose an interactive graph from the ‘Interactive Graph’ link. If an interactive graph is preferred, select a blank summary graph from the link. Make sure the blank graph accepts the same number of ratio values as the number of plants in the study.

      Once the blank graph is chosen, enter the Plant Mass/N.S. Usage ratios for all plants in the study into the interactive squares in the data grid. The graph will generate a bar for each plant in the study. The investigator will be able to easily identify the plant or plants that qualify as the ‘Best Drought Resistant Plants’.