Key insights for improved climate change adaptation strategies: Assessing chilling and heat requirements of Prunus cultivars (Prunus sp.) in warm climate regions

Abstract

Given the influence of climate change, sustain productivity of stone fruit trees is considered a major concern for growers, especially in warm areas where temperature is a crucial determinant of phenology. Sustainable fruit tree orchards depended on satisfying the chilling requirements of cultivars to trigger dormancy release and heat requirements to blossom correctly. Yet determining agroclimatic requirements are essential for predicting cultivar performance and selecting suitable production areas. To support this challenge, our study was conducted to expand the knowledge of agroclimatic requirements of cultivars of Prunus species growing in warm areas. Thus, Partial Least Squares (PLS) regression was employed to compute chilling requirements (CR) using the Dynamic Model (in Chill Portions (CP)) and heat requirements (HR) using the Growing Degree Hours Model (in (GDH)). PLS regression was employed to establish a correlation between long-term phenological observations and temperature records of 7 peach, 5 apricot, and 11 plum cultivars grown in Tunisia. The findings from the PLS regression revealed that the chilling and forcing periods appeared discontinuous. Overlaps or transition periods between the two phases were determined. For peach cultivars, the CR varied from 20 in early flowering cultivars to 63.4 CP in late flowering cultivars and the HR from 4381 to 6556 GDH. For apricot cultivars, the CR ranges from 45.3 to 47.9 CP and the HR from 5567 to 8647 GDH. For plum cultivars, the CR spans from 36.2 to 62.6 CP and the HR from 4999 to 7907 GDH. The main determinant of the flowering of the studied cultivars is the warm mean temperatures occurring during the chilling period. Our findings represent an advance regarding the global knowledge of Prunus temperature requirements which can aid in the adaptation of the stone fruit sector to climate change and mitigation of its impacts.