fruclimadapt (version 0.4.5)

color_potential: Evaluation of weather conditions for anthocyanin formation in apple skin

Description

This function estimates the number of days that can be considered as highly favorable or unfavorable for anthocyanin accumulation in the skin of red apple cultivars during a user defined pre-harvest period (30 days by default). A highly favorable day (Cool day) is considered when the daily maximum temperature is below 26ºC, a highly unfavorable day (Hot day) when the minimum temperature is above 20ºC (Lin-Wang et al, 2011). It also calculates an empirical index in which daily thermal amplitude is corrected to account for the effective range of temperatures for anthocyanin accumulation in the skin (TA_cef). The index considers that daily temperatures above 26ºC are increasingly less favorable for anthocyanin formation, and thus calculates a corrected maximum temperature using a linear function up to 35ºC, where it is left constant at a value of 16, so that the adjusted daily thermal amplitude for Tmax>26ºC is smaller than the observed. The average of maximum and minimum temperatures during the same period is also provided. The function allows testing for several harvest dates.

Usage

color_potential(climdata, harvest, span = 30)

Value

dataframe with the number of highly favorable (Cool_d) and unfavorable (Hot_d) days for apple red color, as well as the sums of the observed (TA_obs) and effective (TA_cef) daily thermal amplitudes. The average of the maximum (Tmax_avg) and minimum (Tmin_avg) temperatures for each year (Year) in the series during the 30 days previous to each harvest date (Day_h) is also provided.

Arguments

climdata

a dataframe with daily maximum and minimum temperatures. Must contain the columns Year, Month, Day, Tmax, Tmin.

harvest

a vector with expected harvest days (expressed as day of the year)

span

the period (in days) before harvest that will be analyzed. By default, this parameter is set in 30 days.

Author

Carlos Miranda,

References

Lin-Wang K, Micheletti D et al, 2011. High temperature reduces apple fruit colour via modulation of the anthocyanin regulatory complex. Plant, Cell and Environment 34, 1176-1190.

Examples

# Select the appropiate columns from Tudela_DW example dataset, create
# a vector or harvest dates and estimate the number favorable and 
# unfavorable days on each year in the dataset.
library(magrittr)
library(dplyr)
Weather <- Tudela_DW %>%
   select(Year, Month, Day, Tmax, Tmin) %>% 
   filter (Tudela_DW$Year<=2002)
harvest <- c(225, 250, 275)
Color_assess <- color_potential(Weather, harvest)