Transpiration {pvldcurve}

Leaf transpiration

Description

Calculates transpiration of a plant part from experimentally determined weight loss per time unit and double-sided leaf area.

Usage

Transpiration(data, sample = "sample", date.and.time = "date.and.time",
  fresh.weight = "fitted.fw", leaf.area = "leaf.area",
  output.unit = "mmol")

Arguments

data

data frame with columns of equal length containg at least columns with the time (and date) of the fresh weight measurements as well as columns with the measured fresh weights (g) and the single-sided leaf area (cm^2) of the sample. The data is to be ordered chronologically by sample. A column containing the sample IDs is optionally required if several samples were measured.

sample

optional name of the column in data containing the sample ID; default: "sample"

date.and.time

optional name of the column in data containing the time of the fresh weight measurements as class POSIXct; default: "date.and.time"

fresh.weight

optional name of the column in data containing the numeric fresh weight values (g); default: "fitted.fw"

leaf.area

optional name of the column in data containing the numeric single-sided leaf area values (cm^2); default: "leaf.area"

output.unit

optional; possible values: "mg" or "mmol"; defines whether transpiration is given in mmol m^-2 s^-1 (Default) or in mg m^-2 s^-1

Details

Transpiration (mmol s^-1 m^-2) is calculated as:

T = \Delta FM * 1000 * (\Delta t * 60 * LA * 2 /10000 * 18.01528)^-1

whereas T = transpiration, \DeltaFW = reduction of fresh weight (g), \Deltat = time unit (min), LA = single-sided leaf area (cm^2)

Value

The original data frame extended by a numeric column with the transpiration (mg s^-1 m^-2 or mmol s^-1 m^-2) of the double-sided leaf area. The first value of each sample is NA, since transpiration values are computed from row i and i-1.

Examples

# get example data and allocate
df <- WeatherAllocation(leaf_drying_data, weather_data)

# extend df by transpiration in mmol s^-1 m^-2
df_with_transpiration <- Transpiration(df, fresh.weight = "fresh.weight")

# extend df by transpiration in mg s^-1 m^-2
df_with_transpiration <- Transpiration(df, fresh.weight = "fresh.weight", output.unit = "mg")