2019 ASHS Annual Conference

Red drupelet reversion is a disorder where drupelets on ripe blackberries (Rubus subgenus Rubus) revert from black to red color during or after postharvest storage. This condition can have a negative impact on consumer appeal as consumers generally prefer blackberries to have a uniform, black color with a glossy appearance. The incidence and severity of red drupelet reversion can be affected by cultural factors including mechanical damage, delayed postharvest cooling, heavy rainfall, and excessive nitrogen application. Blackberry genotypes also differ in their susceptibility to red drupelet reversion. Genotypes with firm fruit have been shown to experience lower rates of reversion than soft-fruited genotypes. A study was conducted in 2018 at the University of Arkansas Fruit Research Station in Clarksville, AR to test the effect of harvest time and fruit temperature on red drupelet reversion in seven cultivars and advanced breeding selections. The seven genotypes were chosen to represent a spectrum of fruit textures in the University of Arkansas blackberry breeding program. Two replicate clamshells were harvested from each genotype on two dates approximately one week apart at four different times of day (7 AM, 10 AM, 1 PM, and 4 PM) and surface temperature of the fruit was measured during harvest. Fruit was then held in cold storage at 4 ⁰C for seven days and returned to room temperature before measuring the percent of berries with three or more reverted drupelets per clamshell and performing compression to evaluate fruit texture. Analysis of variance was performed with the data analyzed as a split-plot design under a gamma distribution. Blackberries harvested at earlier times of day showed lower incidences of reversion, with the lowest percent reverted berries at 7 AM. Additionally, firmer genotypes, such as the ‘crispy’ selection A-2453, had lower percent reversion while softer genotypes, such as Black Magic™, had higher incidences of reversion.