Challenges in predicting climate change impacts on pome fruit phenology

Area of Science:

• Horticulture
• Climate Science
• Phenology

Background:

• Accurate prediction of pome fruit full bloom timing is crucial for agricultural management.
• Climate change poses a significant threat to fruit production by altering environmental cues.
• Existing phenological models vary in their ability to predict responses to climate change.

Purpose of the Study:

• To compare predictions of full bloom timing using two different models under climate projection data.
• To investigate the sensitivity of the sequential chill-growth model to climate perturbations.
• To assess the suitability of different models for climate change impact analyses in pome fruits.

Main Methods:

• Applied climate projection data to fixed thermal time and sequential chill-growth models.
• Utilized seven apple and pear varieties across two Australian locations.
• Conducted four simulations representing diverse physiological requirements across five Australian locations.

Main Results:

• The fixed thermal time model consistently predicted earlier full bloom.
• The sequential chill-growth model produced mixed results, with lengthening chill periods and contracting growth periods observed.
• Model outcomes were influenced by the relative dominance of chill and growth components under warming conditions.

Conclusions:

• The fixed thermal time model is unsuitable for climate projection analyses due to its simplistic structure and exclusion of winter chill.
• The sequential chill-growth model offers greater complexity but still has limitations for impact analyses.
• Accurate representation of physiological processes is essential for predicting phenological shifts under climate change, necessitating further model development.