2014 ASHS Annual Conference

Flesh firmness of blackberry fruits is critical for successful postharvest handling. Therefore, this trait is a priority in the development of new cultivars in breeding programs across the U.S. and world. The University of Arkansas blackberry breeding program has released a number of cultivars with excellent postharvest quality. The program has a wide range of genotypes with exceptional firmness and texture. Crispy and exceptionally firm fruits have been identified. Two thornless Arkansas selections have this trait, A-2453T and A-2454T. After storage for 7-14 d, they maintain firmness, crispiness, and low color reversion (one or more drupelets turning red from black after harvest; an important problem for the blackberry fresh-market industry) beyond that of existing cultivars. This is of importance, because fresh-market potential is determined by how a genotype responds to storage and handling. The objective of this study was to characterize the fruit morphology of crispy blackberry fruits, determine the components contributing to this trait, and determine the relationship between fruit firmness and color reversion. Shiny-black fruits of 15 blackberry genotypes were harvested into 0.24 L clamshells during the 2013 season. Samples were divided in two groups. One group was evaluated for color reversion at harvest and after one week of cold storage at 5 °C utilizing a quantitative score. In the other group, firmness analysis was performed. For this, compression and penetration forces were measured on different parts of the fruit (drupelet, receptacle, and the entire fruit) at harvest utilizing a texture measurement device. For penetration and compression, 1.0 mm, and 7.2 cm cylinder probes were utilized, respectively. After one week of cold storage, the two crispy genotypes along with A-2218 presented low levels of color reversion and were superior to other selections and cultivars. ‘Natchez’ and selection A-1960T, although having improved postharvest handling potential than many cultivars, had higher numbers of fruits having at least four drupelets with color reversion. Crispy genotypes showed the highest compression firmness values compared to non-crispy genotypes. Compression values of crispy genotypes averaged 13.0 N, almost double than ‘Ouachita’ with 7.1 N. Skin drupelet penetration force showed a similar trend as compression force. Lastly, crispy genotypes also showed a higher receptacle penetration force, reflecting enhanced firmness of the internal core of the berry. These results are promising, showing superior flesh fruit firmness, low color reversion, superior postharvest quality and shipping potential of these crispy genotypes.