Fruit set and berry weight of four rabbiteye blueberry cultivars following exposure to sub-freezing temperatures during flowering.

摘要

Two spring freezes in Griffin, Georgia during the flowering period in 2008 provided an opportunity to monitor freeze-damage effects on fruit set and fruit weight of four rabbiteye blueberry cultivars under field conditions. Minimum temperatures of -4.2 and -3.5 degrees C occurred on March 9 and March 25, respectively. The estimated dates of 50% open flowers for the cultivars were: Climax, March 23; Alapaha, March 30; Tifblue, April 2, and Ochlockonee, April 10. Initial visual damage estimates (i.e., corolla browning) 3 to 4 days following the last freeze suggested nearly a total crop loss for 'Climax' and 'Alapaha', and moderate to severe crop loss for 'Tifblue' and 'Ochlockonee'. However, more quantitative estimates of fruit set after counting several thousand flowers and fruit for each cultivar revealed different results than initially anticipated. 'Climax' and 'Tifblue' did suffer great reductions in fruit set, averaging <8% fruit remaining 6 to 8 weeks after flowering. However, 'Alapaha' managed to maintain fruit set of more than 36%, and 'Ochlockonee' fruit set was greater than 50%. There were no apparent effects of the freeze on remaining fruit weights. These data indicate that there are differences in fruit set of rabbiteye cultivars following spring freezes during flowering. Hence, growers may want to consider the more cold hardy cultivars in their planting operations if their growing areas are subject to freezes in early to mid-spring.