Southern highbush blueberries result from hybridizations among the northern highbush blueberry (Vaccinium corymbosum L.) and other Vaccinium spp. possessing southern U.S. adaptation attributes. Southern highbush blueberry cultivars provide southern blueberry producers advantages over the native rabbiteye blueberry (Vaccinium virgatum Ait.), the foundation of the southern blueberry industry for the last century. Cultivars possessing attributes including high fruit quality and early ripening period provide growers greater assurance of participating in the more lucrative U.S. fresh market as opposed to processing markets. ‘Pearl’ is a new southern highbush blueberry (Vaccinium spp. hybrid) developed and released by the U.S. Department of Agriculture–Agricultural Research Service (USDA-ARS) that is a midseason southern highbush blueberry cultivar possessing favorable fruit quality attributes including very large (greater than 3 g) light blue berries having very good flavor and firmness, small picking scars, and a ripening period that is 10 to 14 d earlier than the earliest ripening rabbiteye blueberry cultivars. ‘Pearl’ has additional use in that it can be either hand or mechanically harvested.
Origin and Description
‘Pearl’ (Fig. 1) was tested as MS 812 and originated from a cross of ‘Bluecrisp’ × ‘Magnolia’ (Spiers et al., 1996) made by Arlen Draper USDA-ARS, Beltsville, MD, and was selected by him in 1999 at the USDA-ARS Thad Cochran Southern Horticulture Laboratory in Poplarville, MS. Both ‘Bluecrisp’ and ‘Magnolia’ are southern highbush cultivars: the pedigree of ‘Bluecrisp’ (USPP 11,033) is unknown; ‘Magnolia’ was derived from the cross (‘Harrison’ × ‘Avonblue’) × Fla72-5; both Harrison and Avonblue are also southern highbush cultivars. (Fla72-5 resulted from a cross of Fla67-8 × Fla65-28; Fla67-8 resulted from a cross of E-66 × Fla61-3). E-66 was a northern highbush selection from Arthur Elliott in Michigan, and Fla61-3 resulted from a cross of [‘Earliblue’ × Fla4A (V. darrowii)] × 37-9. It is likely that 37-9 resulted from selfing of the northern highbush selection US 37. Fla65-28 resulted from a cross of A [Fla4B (V. darrowi) × V. virgatum clone #3] × (‘Berkeley’ × Fla4B) × E-22. E-22 is another northern highbush selection from Arthur Elliott. Thus, ‘Pearl’ is a complex hybrid containing primarily Vaccinium corymbosum L. (4×) and V. darrowi Camp (2×) with a small amount of V. virgatum Ait. (6×) through ‘Avonblue’ (Sharpe and Sherman, 1977).
Plants of ‘Pearl’ (Fig. 2) are vigorous and productive with dark green foliage and have a moderately spreading growth habit and narrow crowns. ‘Pearl’ produces very large (greater than 3.0 g), attractive, light blue, firm berries with excellent flavor and small picking scars. Through comparison of flowering dates with those of other blueberry cultivars with known chilling requirements, ‘Pearl’ is estimated to have a chilling requirement of 400 to 450 h below 7 °C based on a comparisons of its flowering dates to those of other blueberry cultivars with known chilling requirements. ‘Pearl’ is expected to perform well not only in the gulf coast region and other areas within USDA hardiness zones 7a through 9a where southern highbush blueberry cultivars with low to moderate chilling requirements are grown successfully.
‘Pearl’ southern highbush blueberry fruit during ripening.
Citation: HortScience horts 48, 1; 10.21273/HORTSCI.48.1.130
‘Pearl’ southern highbush blueberry fruit during ripening.
Citation: HortScience horts 48, 1; 10.21273/HORTSCI.48.1.130
‘Pearl’ southern highbush blueberry fruit during ripening.
Citation: HortScience horts 48, 1; 10.21273/HORTSCI.48.1.130
Performance
Plant and berry attributes of ‘Pearl’, two standard southern highbush cultivars, O’Neal and Star, and two early-ripening rabbiteye blueberry cultivars, Climax and Premier, were evaluated over six years (2005–10) at Stone County, MS, near the DeSoto National Forest in south–central Mississippi (Table 1). Plants were established in 2001 and grown in an acidic soil (pH 5.2) amended with 200 m3 of pine bark per ha under drip irrigation using recommended production practices. In comparison with ‘O’Neal’ and ‘Star’, ‘Pearl’ consistently had greater plant vigor and cropload. Inconsistent croploads were noted periodically for both ‘O’Neal’ and ‘Star’, both predisposed to injury to flower buds and developing fruit during late spring frost events at this site (data not shown). Both blooming and ripening periods of ‘Pearl’ were 10 to 12 d after the two southern highbush cultivars and although blooming periods were similar to the rabbiteyes, ‘Pearl’ ripened 14 to 20 d earlier. Field evaluations demonstrated that important berry quality attributes including berry size, color, and firmness were consistently better for ‘Pearl’ than all cultivars evaluated and that berries had small picking scars and good flavor. Additional laboratory evaluations of berry quality were conducted in 2004 and 2010 (Table 2) from eight replications of berry samples harvested each year. Berry size was determined by weighing 100 berries of each of the cultivars each season. Berry firmness measurements were obtained from 20 berry samples run on a Firmtech II (Bioworks Corp., Stillwater, OK). Soluble solids content and pH were determined from juice extracted from a puree of a 40-g sample placed into a commercial Waring® blender (Dynamics Corp. of America, Hartford, CT) and strained through cheesecloth. A handheld temperature-compensating refractometer (Leica Microsystems AR 200, Welzar, Germany) was used to measure juice soluble solids. pH was measured using an AR20 pH/Conductivity meter (ThermoFisher Scientific Corp., Waltham, MA).
Ratings of fruit and plant characteristics of ‘Pearl’, two southern highbush (‘O’Neal’ and ‘Star’), and two rabbiteye (‘Climax’ and ‘Premier’) standard cultivars over a six-year period (2005–10) at Wiggins, MS.z
Laboratory evaluations of fruit and plant characteristics of Gupton, two southern highbush (‘O’Neal’ and ‘Star’) and two rabbiteye (‘Climax’ and ‘Premier’) standard cultivars (2004, 2008) at Stone County, MS.
In comparison with other cultivars evaluated, berry size was greatest for ‘Pearl’ (3.1 g). Berry firmness of ‘Pearl’ was also notably greater than standard southern highbush and rabbiteye blueberry cultivars. Berry pH of ‘Pearl’ was lower than ‘Climax’, and soluble solids content was comparable to that of the other standard cultivars.
Preliminary grower trials indicated that ‘Pearl’ is likely suitable for mechanical harvest, although more extensive testing is advised. Although ‘Pearl’ has a degree of self-fertility, it should be planted with other southern highbush blueberry cultivars having similar blooming periods to enhance pollination and fruit set. ‘Pearl’ propagates readily from softwood cuttings taken from new growth in late spring or late summer and from hardwood cuttings taken in the winter and through micropropagation.
Availability
‘Pearl’ is a public domain blueberry cultivar developed by the USDA-ARS Thad Cochran Southern Horticultural Laboratory where a limited supply of rooted cuttings, cutting wood, and tissue-cultured plants are available to certified nurserymen. Written requests for plant materials should be sent to Dr. Stephen Stringer, USDA-ARS Southern Horticulture Laboratory, P.O. Box 287, Poplarville, MS 39470. Genetic materials of this release are deposited in the National Plant Germplasm Repository at Corvallis, OR, where it is available for research purposes and commercial development.
Literature Cited
Sharpe, R.H. & Sherman, W.B. 1997 ‘Avonblue’ blueberry HortScience 12 510
Spiers, J.M., Gupton, C.L. & Draper, A.D. 1996 ‘Jubilee’, ‘Magnolia’, and ‘Pearl River’ southern highbush blueberries Acta Hort. 446 155 157
