2016 Volume 15 Issue 2 Pages 179-187
To clarify cultivar variations of blueberry fruit cracking susceptibility, influences of the weight, morphology, and water absorption on fruit cracking were investigated. Fruit cracking rates ranged from 0 to 56.7%. A positive correlation between fruit cracking rates and fruit weights was found in moderate crack-susceptible cultivars. Highly crack-susceptible cultivars, ‘Duplin’, ‘Star’, and ‘Tifblue’, had relatively large calyxes and often cracked from fruit apexes. In contrast, low crack-susceptible cultivars, ‘Duke’, ‘Hannah’s Choice’, ‘New Hanover’, and ‘Sampson’, had relatively small fruit shape indexes and cracked from the sides and pedicel ends of fruit except for ‘Sampson’, in which no cracks occurred. These results indicate that cultivar variations in cracking susceptibility are affected by morphological factors through stress distribution. Concerning 23 cultivars, however, there were no correlations among fruit cracking rates and weights, morphology, and water absorption. Therefore, these factors may not independently determine fruit cracking susceptibility. Regarding ‘Star’ and ‘Tifblue’ harvested on the same day, the calyx basin diameter, pedicel scar diameter, and fruit cracking rate increased with the fruit weight. In these highly crack-susceptible cultivars, crack-susceptibility may increase as the result of the changing fruit morphology and the increasing amount of water absorption associated with increasing fruit size. However, no partial correlations were detected when the controlling variable was the fruit weight.
