Agroclimatic indicators and maize yield variability in Slovenia: A PCA and correlation analysis

This study examines the influence of agroclimatic indicators on the variability of maize crop yield in Slovenia. Principal Component Analysis (PCA) was conducted on three categories of agroclimatic indicators: temperature and heat stress during the growing season, spring frost conditions, and precipitation conditions during the growing season. Six principal components were identified, each accounting for at least 64% of the variability in the initial datasets. Spearman correlation analysis between the principal components and maize yield at two trial sites revealed statistically significant correlations for three components: 'high precipitation conditions,' 'temperature conditions during the growing season,' and 'maize plant heat stress conditions.' Maize yield at the trial sites exhibited a positive correlation with slightly above-average precipitation during the growing season, whereas a weak negative correlation was observed with elevated growing season temperatures and maize plant heat stress conditions. The historical spatial distribution of the principal components indicated average conditions across most of the region, with some regional variations. Future projections suggest an increase in the frequency of high precipitation events, primarily in regions that already experienced sufficient precipitation historically. Warmer growing season conditions and significantly more frequent heat stress conditions are also anticipated under RCP4.5 and RCP8.5 scenario, particularly in the southwestern, central, and eastern parts of the country. The results of the study suggest a potential decline in future maize yields at the trial sites due to the projected increase in temperature and heat stress conditions. These findings offer valuable insights for agricultural planning and climate adaptation strategies in Slovenia. • Six principal components were calculated to represent the agroclimatic variability. • Positive correlation between maize yield and high summer precipitation conditions. • Negative correlation between maize yield and elevated growing season temperatures. • A substantial future increase is projected in 'maize plant heat stress conditions'.