Transpiration: Leaf transpiration
In pvldcurve: Simplifies the Analysis of Pressure Volume and Leaf Drying Curves

Description Usage Arguments Details Value Examples

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

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

`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

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

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

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

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.

# 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")