Blueberry Splitting Tendencies as Predicted by Fruit Firmness

Authors: Shaw, Donna; Spiers, James; Stringer, Stephen

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 2/8/2007
Publication Date: 4/1/2007
Citation: Marshall, D.A., Spiers, J.M., Stringer, S.J. 2007. Blueberry Splitting Tendencies as Effected by Fruit Firmness. HortScience. 42(3):443.

Interpretive Summary: In selecting blueberry progeny for advancement in breeding programs geneticists use a variety of measurements to determine quality of the fruit. Firmness values are useful for determining fruit suitability for mechanical harvesting and long-distance shipping. Fruit were measured for firmness using a QTS25 and a FirmTech2. The findings indicate that firmness measured as deformation or modulus with the QTS25 can predict splitting tendencies for most cultivars, but firmness measured with the FirmTech2 cannot. In general, firmer fruit will have a higher tendency for splitting. This suggests that if geneticists select for the favorable trait of very firm fruit they may also be selecting for the negative trait of splitting tendency. Nevertheless, the one outlying selection (MS614) exhibiting extreme firmness and splitting resistance has the fruit characteristics that are very desirable to cultivar release and commercial production. This selection would have been discarded if firmness values alone were used to denote splitting indicating that regardless of firmness values a laboratory test to determine splitting susceptibility would be beneficial to geneticists as a truer indicator of germplasm splitting tendencies.

Technical Abstract: To improve the quality of berries during handling and shipping, blueberry breeders have strived to develop a fruit that is firm in texture. However previous studies show blueberry cultivars with firmer fruit were more susceptible to splitting. This study was further investigates the correlation between splitting susceptibility and fruit firmness. Cultivars and selections of rabbiteye (Vaccinium ashei) and Southern Highbush (interspecific hybrids primarily consisting of V corymbosum X) blueberry were used to determine whether or not berries displaying higher fruit firmness also have a higher incidence of splitting. Three distinctly different measurements of berry firmness were obtained using two instruments: QTS25 and FirmTech2. Berries were subsequently submitted to laboratory procedures to induce splitting. In general firmness measured as either deformation or modulus with the QTS25 correlated with splitting tendencies. Yet there are exceptions that need to be further examined.