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Chilling Requirement and Post-rest Heat Accumulation as Related to Difference in Time of Bloom Between Peach and Western Sand Cherry


The basis for the difference in time of bloom between ‘Redhaven’ peach [Prunus persica (L.) Batsch] and western sand cherry (Prunus besseyi Bailey) clone ‘Cornell-Geneva (CG) 3-24’ was investigated. Based on 3 years of field observation, average bloom date (50% of buds) of ‘Redhaven’ was 9 days earlier than ‘CG 3-24’. Greenhouse forcing of field-collected shoots and artificially chilled trees suggested that the flower bud chilling requirement of these two clones is similar. Forcing of artificially chilled trees under different post-rest temperature regimes revealed that the base temperature for flower bud heat accumulation was lower in ‘Redhaven’ than in ‘CG 3-24’ (4.3° vs 7.0°C, respectively). Values of Q10 for flower bud development were 2.2 and 2.8 for ‘Redhaven’ and ‘CG 3-24’, respectively. These results suggest that the basis for difference in time of bloom is due to a difference in the base temperature for heat accumulation and is not related to chilling requirement.