A 15-year long assessment of cold hardiness of apricot flower buds and flowers during the blooming period

Abstract

Long-term examinations are important for accurately dissecting the genotypic and environmental factors of and for predicting the possible impacts of climate change on quantitative traits, such as the frost tolerance of apricot generative organs during the floral developmental period. In our experimental work the cold hardiness of flower buds and flowers of three apricot cultivars [‘Ceglédi bíborkajszi’ (CBK), ‘Gönci magyar kajszi’ (GMK) and ‘Rózsakajszi C.1406’ (RK)] was studied systematically in different phenological stages, applying a standardised artificial freezing test protocol on samples collected from the orchard during a period of 15 consecutive years. Based on the results, both the genotypes and the years were highly significant components of frost tolerance; at the early phases the greater effect of years, while at the later stages that of the genotypes were detected. RK was frost tolerant and more stable across the years, while CBK was the most frost sensitive, which was accompanied by a significantly higher sensitivity to seasonal differences. Positive correlation was found between the starting time of blooming and frost tolerance of flowers, the significance of which intensified with the frost sensitivity of the apricot genotype. Significant associations were identified between various meteorological parameters of the 8-month period prevailing flowering and frost tolerance of apricot flowers during blooming. Possible effects of climate change on the local weather conditions were also detected with significant impacts on the phenological processes of floral buds, on the timing of flowering and on frost tolerance.