Performance of Southern Highbush Blueberry Cultivars Under High Tunnels in Florida

A study was conducted over two southern highbush blueberry (Vaccinium corymbosum x Vaccinium darrowi) seasons in a grower field in Florida. The objective was to compare the early fruit weight of southern highbush blueberry cultivars in high tunnels and in open fields. Four treatments were tested using combinations of two southern highbush blueberry cultivars (Snow Chaser and Springhigh) and two production systems (open fields and 18-ft-high tunnels). The results indicated that there was a significant effect of the production systems on the number of days with air temperatures at or near freezing (<= 34 degrees F), and maximum and minimum air temperatures. The minimum air temperature in open-field plots reached approximate to 19 and 21 degrees F (61 freezing or near-freezing events) in the 2009-10 and 2010-11 seasons, respectively, whereas the minimum air temperatures inside the high tunnels were approximate to 32 and 33 degrees F, respectively, during the same seasons (only 3 days at <= 34 degrees F). This indicated that using high tunnels was an effective means to avoid freezing air temperatures in blueberries. In the first season, the cumulative early fruit weight was the highest in plots planted with 'Snow Chaser' inside the high tunnels (approximate to 10 tons/acre), while the combined production of the two cultivars in the open fields did not reach 1 ton/acre until the end of the early harvests. The following year, there were no differences in the cumulative early fruit weight of both cultivars when planted in the open fields (2.2 tons/acre) and the cumulative fruit yields of 'Springhigh' and 'Snow Chaser' growing inside the high tunnels was twice and four times higher, respectively, than the early fruit production obtained in the open fields. These data showed the profound effect of high tunnels on flower protection and fruit set. High tunnels reduced water use for freeze protection. The total volume used in the open fields during the freezing or near-freezing days was approximate to 2.5 acre-inch/acre per 8 hours of freeze protection, whereas only 1/10 of that volume was applied inside the structures.