How sensitive are the flower parts of the sweet cherry in sub‐zero temperatures? Use of differential thermal analysis and critical temperatures assessment

ABSTRACT Unpredictable late spring frosts are a major risk to sweet cherry, and information on the critical temperatures of new cultivars are limited. The objective of this study was to examine the response of cherry flower parts (sepal, pedicel, receptacle, petal, stamen and pistil) to freezing stress by using differential thermal analysis at different stages of bud development for consecutive two years. In order, from the most tolerant flower part to the least tolerant on average temperatures at which 50% of the flower buds were killed, were the stamen, pistil, petal, pedicel, receptacle and sepal. Additionally, a significant cultivar effect was found on freeze damage to the stamen, pistil, petal, pedicel, receptacle and sepal. In general, flowering parts of ‘Lambert’, ‘0900‐Ziraat’ and ‘Erzincan Macar’ were the more sensitive to freezing, whereas flowering parts of ‘Stella’, ‘Vista’ and ‘Early Burlat’ were the most freezing‐tolerant during bud development stages. These results can give growers with important information that can be beneficial to them when choosing cherry cultivars for their new orchard. However, our findings and corresponding discussion highlight the importance of considering field observations as one of the factors for objective interpretation of critical temperatures of flower parts derived from artificial freeze tests.