chillR: Statistical Methods for Phenology Analysis in Temperate Fruit Trees

The phenology of plants (i.e. the timing of their annual life phases) depends on climatic cues. For temperate trees and many other plants, spring phases, such as leaf emergence and flowering, have been found to result from the effects of both cool (chilling) conditions and heat. Fruit tree scientists (pomologists) have developed some metrics to quantify chilling and heat (e.g. see Luedeling (2012) <doi:10.1016/j.scienta.2012.07.011>). 'chillR' contains functions for processing temperature records into chilling (Chilling Hours, Utah Chill Units and Chill Portions) and heat units (Growing Degree Hours). Regarding chilling metrics, Chill Portions are often considered the most promising, but they are difficult to calculate. This package makes it easy. 'chillR' also contains procedures for conducting a PLS analysis relating phenological dates (e.g. bloom dates) to either mean temperatures or mean chill and heat accumulation rates, based on long-term weather and phenology records (Luedeling and Gassner (2012) <doi:10.1016/j.agrformet.2011.10.020>). As of version 0.65, it also includes functions for generating weather scenarios with a weather generator, for conducting climate change analyses for temperature-based climatic metrics and for plotting results from such analyses. Since version 0.70, 'chillR' contains a function for interpolating hourly temperature records.

Version: 0.75
Depends: R (≥ 3.5.0)
Imports: assertthat, dplyr, ecmwfr, fields, GenSA, ggplot2, graphics, grDevices, httr, jsonlite, Kendall, lubridate, magrittr, metR, patchwork, pls, plyr, progress, purrr, R.utils, raster, Rcpp, RCurl, readxl, reshape2, rlang, RMAWGEN, scales, stats, stringr, tidyr, utils, XML
LinkingTo: Rcpp
Suggests: knitr, rmarkdown, testthat
Published: 2023-11-27
DOI: 10.32614/CRAN.package.chillR
Author: Eike Luedeling ORCID iD [aut, cre], Lars Caspersen ORCID iD [aut], Eduardo Fernandez ORCID iD [aut]
Maintainer: Eike Luedeling <eike at>
License: GPL-3
NeedsCompilation: yes
Materials: README
CRAN checks: chillR results


Reference manual: chillR.pdf
Vignettes: PhenoFlex
Producing hourly temperature records for agroclimatic analysis


Package source: chillR_0.75.tar.gz
Windows binaries: r-devel:, r-release:, r-oldrel:
macOS binaries: r-release (arm64): chillR_0.75.tgz, r-oldrel (arm64): chillR_0.75.tgz, r-release (x86_64): chillR_0.75.tgz, r-oldrel (x86_64): chillR_0.75.tgz
Old sources: chillR archive

Reverse dependencies:

Reverse imports: decisionSupport
Reverse suggests: ChillModels


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