fruclimadapt (version 0.4.5)

sunburn: Evaluation of weather conditions for sunburn in apple fruit surface

Description

This function estimates the number of days in which apple fruit surface temperature (FST) exceeds the thresholds indicated by Rackso and Schrader (2012) for two types of sunburn damages.

Usage

sunburn(climdata, first_d, last_d)

Value

data frame with the number of days within the assessed period(s). Contains the columns Year, Harvest (values from last_d), SB_browning and SB_necrosis.

Arguments

climdata

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

first_d

Numeric, it is the first date, indicated as day of the year (DOY), in the assessment.

last_d

a vector with the last(s) dates for the assessment (as DOY). Examples could be harvest dates for several cultivars.

Author

Carlos Miranda,

Details

Sunburn necrosis (SN), the most severe type of sunburn, with a dark brown or black necrotic spot on the exposed fruit surface is considered to appear when FST reaches 52ºC. Sunburn browning (SB) is the most prevalent type of sunburn on attached sun-exposed apples (acclimated to high light). The threshold temperature for SB is set in 46ºC, and corresponds to the most sensitive apple cultivars (like Cameo or Honeycrisp).

FST is estimated from daily maximum air temperature using the expression proposed by Schrader et al (2003).

References

Rackso J and Schrader LE, 2012. Sunburn of apple fruit: Historical background, recent advances and future perspectives. Critical Reviews in Plant Sciences 31, 455-504.

Schrader L, Zhang J and Sun J, 2003. Environmental stresses that cause sunburn of apple. Acta Horticulturae 618, 397-405.

Examples

# Create one vector with start date (i.e. hand thinning) and a vector 
# with harvest dates to test sunburn risk for several cultivars using.
library(magrittr)
library(dplyr)
library(lubridate)
Thinning_d <- 135
Harvest_d <- c(225,245,260)
Sunburn_risk <- sunburn(Tudela_DW,Thinning_d, Harvest_d)