Performance of Southern Highbush Blueberry Cultivars Under High Tunnels in Florida

Abstract

<jats:p>A study was conducted over two southern highbush blueberry (<jats:italic>Vaccinium corymbosum</jats:italic> × <jats:italic>Vaccinium darrowi</jats:italic>) 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 °F), and maximum and minimum air temperatures. The minimum air temperature in open-field plots reached ≈19 and 21 °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 ≈32 and 33 °F, respectively, during the same seasons (only 3 days at ≤34 °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 (≈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 ≈2.5 acre-inch/acre per 8 hours of freeze protection, whereas only 1/10 of that volume was applied inside the structures.</jats:p>

A Review for Southern Highbush Blueberry Alternative Production Systems

“…Southern highbush blueberry production in unheated high tunnels ( Figure 3) has been studied in different countries, including Japan [11], Spain [12], Portugal [13], Chile [2], and the United States [14]. High tunnels increase soil and air temperature around the plant [6,15,16], reducing cold stress or damage [16] and enhancing heat unit accumulation during winter and early spring [11,14,16,17]. Warmer temperatures during the cold parts of the season are widely accepted as the reason for earlier fruit ripening in high tunnels [11,14,16,17].…”

“…High tunnels increase soil and air temperature around the plant [6,15,16], reducing cold stress or damage [16] and enhancing heat unit accumulation during winter and early spring [11,14,16,17]. Warmer temperatures during the cold parts of the season are widely accepted as the reason for earlier fruit ripening in high tunnels [11,14,16,17]. For example, the SHB cultivars 'Snowchaser', 'Emerald', 'Jewel', and 'O'Neal' grown in high tunnels were ready to harvest nearly a month earlier than the same cultivars grown in open field conditions [14,16,18].…”

“…Warmer temperatures during the cold parts of the season are widely accepted as the reason for earlier fruit ripening in high tunnels [11,14,16,17]. For example, the SHB cultivars 'Snowchaser', 'Emerald', 'Jewel', and 'O'Neal' grown in high tunnels were ready to harvest nearly a month earlier than the same cultivars grown in open field conditions [14,16,18]. High tunnels have supported the northward expansion of SHB cultivation, for example, within the United States to areas in Mississippi where only rabbiteye blueberries were previously cultivated [19].…”

“…High tunnels have supported the northward expansion of SHB cultivation, for example, within the United States to areas in Mississippi where only rabbiteye blueberries were previously cultivated [19]. Additionally, the use of high tunnels can significantly reduce water usage for freeze protection, requiring only one-tenth of the total volume used in the open field [16]. While temperature increases during winter and early spring enhance SHB growth, air and soil temperatures inside high tunnels can quickly surpass plant optimal temperatures during late spring and summer.…”

“…In addition, high tunnels reduce the exchange of convective heat with the surrounding air, and thus, the cooling impact from pine bark beds (if used) may have more negative effects on the plant-level temperature compared to the effects of bark bed in the open field [24]. Therefore, where temperatures drop below 1 • C, growers use micro-sprinklers to increase air humidity inside the tunnel and provide additional freeze protection [16].…”