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library(rio) # Data import
library(metan) # corr_plot() – correlation matrix with visual output
library(ggplot2)This section examines the linear associations among the three vegetative growth traits measured at each harvest:
af_planta, cm² plant⁻¹)n, leaves plant⁻¹)cp, cm)A Pearson correlation matrix with significance stars is produced via metan::corr_plot().

All three traits are expected to be positively and strongly correlated given that they are all driven by the same thermal-time accumulation process.
sessionInfo()
## R version 4.5.1 (2025-06-13 ucrt)
## Platform: x86_64-w64-mingw32/x64
## Running under: Windows 11 x64 (build 26200)
##
## Matrix products: default
## LAPACK version 3.12.1
##
## locale:
## [1] LC_COLLATE=Portuguese_Brazil.utf8 LC_CTYPE=Portuguese_Brazil.utf8
## [3] LC_MONETARY=Portuguese_Brazil.utf8 LC_NUMERIC=C
## [5] LC_TIME=Portuguese_Brazil.utf8
##
## time zone: America/Sao_Paulo
## tzcode source: internal
##
## attached base packages:
## [1] stats graphics grDevices utils datasets methods base
##
## other attached packages:
## [1] ggplot2_4.0.2 metan_1.19.0 rio_1.2.4
##
## loaded via a namespace (and not attached):
## [1] gtable_0.3.6 xfun_0.56 htmlwidgets_1.6.4
## [4] ggrepel_0.9.7 GGally_2.4.0 lattice_0.22-9
## [7] mathjaxr_2.0-0 numDeriv_2016.8-1.1 vctrs_0.7.1
## [10] tools_4.5.1 Rdpack_2.6.6 generics_0.1.4
## [13] tibble_3.3.1 pkgconfig_2.0.3 R.oo_1.27.1
## [16] Matrix_1.7-4 RColorBrewer_1.1-3 S7_0.2.1
## [19] readxl_1.4.5 lifecycle_1.0.5 compiler_4.5.1
## [22] farver_2.1.2 textshaping_1.0.4 ggforce_0.5.0
## [25] codetools_0.2-20 lmerTest_3.2-0 htmltools_0.5.9
## [28] yaml_2.3.12 pillar_1.11.1 nloptr_2.2.1
## [31] tidyr_1.3.2 MASS_7.3-65 R.utils_2.13.0
## [34] reformulas_0.4.4 boot_1.3-32 nlme_3.1-168
## [37] ggstats_0.12.0 tidyselect_1.2.1 digest_0.6.39
## [40] dplyr_1.2.1 purrr_1.2.1 labeling_0.4.3
## [43] splines_4.5.1 polyclip_1.10-7 fastmap_1.2.0
## [46] grid_4.5.1 cli_3.6.5 magrittr_2.0.4
## [49] patchwork_1.3.2 dichromat_2.0-0.1 withr_3.0.2
## [52] scales_1.4.0 rmarkdown_2.30 otel_0.2.0
## [55] lme4_1.1-38 cellranger_1.1.0 ragg_1.5.0
## [58] R.methodsS3_1.8.2 evaluate_1.0.5 knitr_1.51
## [61] rbibutils_2.4.1 rlang_1.1.7 Rcpp_1.1.1
## [64] glue_1.8.0 tweenr_2.0.3 rstudioapi_0.18.0
## [67] minqa_1.2.8 jsonlite_2.0.0 R6_2.6.1
## [70] systemfonts_1.3.1---
title: "Correlation Analysis"
description: "Pearson correlation matrix among leaf area, leaf number, and plant height across all measurement dates and treatments."
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(
cache = FALSE,
comment = "##",
collapse = TRUE,
warning = FALSE,
message = FALSE
)
```
## Overview
This section examines the linear associations among the three vegetative growth
traits measured at each harvest:
- **Leaf area per plant** (`af_planta`, cm² plant⁻¹)
- **Leaf number per plant** (`n`, leaves plant⁻¹)
- **Plant height** (`cp`, cm)
A Pearson correlation matrix with significance stars is produced via
`metan::corr_plot()`.
## Required packages
```{r libraries}
library(rio) # Data import
library(metan) # corr_plot() – correlation matrix with visual output
library(ggplot2)
```
## Correlation plot
```{r corr-plot, fig.cap="Pearson correlation matrix among leaf area, leaf number, and plant height. The lower panel shows scatter plots with a linear smoother; the upper panel shows the correlation coefficient and its significance (*** p < 0.001, ** p < 0.01, * p < 0.05).", fig.width=6, fig.height=6}
import("../df_model_cresc.xlsx") |>
# Select the three growth variables; corr_plot() handles pairwise correlations
corr_plot(af_planta, n, cp)
ggsave("../figs/correlacao.jpg", width = 6, height = 6)
```
::: {.callout-note}
All three traits are expected to be positively and strongly correlated given that
they are all driven by the same thermal-time accumulation process.
:::
## Session information
```{r session-info}
sessionInfo()
```