2019 ASHS Annual Conference

In climacteric fruits, ethylene affects several physiological processes that occur during ripening, such as softening, changes in content of sugars and acids, accumulation of pigments and susceptibility to pathogens. Collectively, these changes can affect fruit quality at harvest. In blueberry fruit, the role of ethylene in ripening has not been very well investigated. We determined ethylene levels in blueberry cultivars ‘Premier’ and ‘Powderblue’ during ripening. Our results indicated that both the cultivars produce ethylene during ripening but at varying levels. Further, we determined the effect of ethephon, a plant growth regulator (PGR) that releases ethylene, on ripening in the two cultivars. Application of ethephon increased fruit ethylene levels by 6-fold and 2-fold on 2 and 5 days after treatment respectively. In addition, ethephon promoted fruit ripening by increasing the proportion of blue (ripe) fruit . To determine fruit quality, ripe fruit were harvested approximately 10 days after the application. In general, all fruit quality characteristics such as fruit texture, weight, juice pH, total soluble acids, and titratable acidity were not affected by ethephon except for a decrease in juice pH in ‘Powderblue’. In contrast, our preliminary data suggests that application of aminoethoxyvinylglycine (AVG, an inhibitor of ethylene biosynthesis) and 1-methylcyclopropene (1-MCP, an inhibitor of ethylene response) did not delay fruit ripening and had no effect on fruit quality attributes at harvest except for an increase in puncture after 1-MCP treatment. We are currently performing RNA-Seq analysis to elucidate the mechanistic role of ethephon/ethylene in blueberry ripening. Further information on the PGR-effect on ripening will be useful to the blueberry industry to manipulate ripening and reduce production costs.