scholarly journals Hydrogen Cyanamide Stimulates Early Foliation of `Misty' Southern Highbush Blueberry

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 537C-537
Author(s):  
J.G. Williamson ◽  
R.L. Darnell
Keyword(s):  
Vegetative Growth ◽  
Fruit Set ◽  
Small Diameter ◽  
Highbush Blueberry ◽  
Full Bloom ◽  
Flower Buds ◽  
Flower Bud ◽  
Hydrogen Cyanamide ◽  
Southern Highbush ◽  
Chilling Treatment

Two-year-old, container-grown `Misty' southern highbush blueberry plants were sprayed to drip with two concentrations of hydrogen cyanamide (HCN) (20.4 g·L–1 and 10.2 g·L–1) after exposure to 0, 150, or 300 hr of continuous chilling at 5.6°C. All plants were sprayed immediately after chilling and placed in a greenhouse for several weeks. The plants were moved outdoors during flowering to increase cross-pollination from nearby `Sharpblue' blueberry plants. HCN sprays killed some of the more advanced flower buds on shoot terminals and on small-diameter wood from the previous spring growth flush. Significantly greater flower bud mortality occurred for the 20.4 g·L–1 HCN sprays than for the 10.2 g·L–1 sprays. Flower buds subjected to 0 hr of chilling were more susceptible to spray burn than flower buds receiving 150 or 300 hr of chilling. Very little flower bud death occurred with the 10.2 g·L–1 HCN rate on plants receiving 300 hr of chilling. Vegetative budbreak was advanced for both HCN treatments compared to controls, regardless of chilling treatment. HCN-treated plants were heavily foliated at full bloom, while non-treated plants had very few to no leaves during bloom. HCN may be useful for stimulating vegetative growth in some southern highbush blueberry cultivars that suffer from poor foliation during flowering and fruit set.

scholarly journals FLOWER BUD HARDINESS OF SOUTHERN HIGHBUSH BLUEBERRY CULTIVARS

HortScience ◽  
1995 ◽  
Vol 30 (3) ◽  
pp. 430d-430
Author(s):  
John R. Clark ◽  
Robert Bourne
Keyword(s):  
Incubation Period ◽  
Minimum Temperature ◽  
Gulf Coast ◽  
Highbush Blueberry ◽  
Blue Ridge ◽  
Flower Buds ◽  
Flower Bud ◽  
Cape Fear ◽  
Southern Highbush

The southern highbush blueberry (Vaccinium spp.) `Blueridge', `Cape Fear', `Cooper', `Georgiagem', `Gulf Coast', and `O'Neal'; the rabbiteye (V. ashei Reade) `Climax'; and the highbush (V. corymbosum L.) `Bluecrop' were evaluated for ovary damage following exposure of flower buds to 0 to 30C in a programmable freezer in Dec. 1993 and Jan. and Feb. 1994. The plants sampled were growing at the Univ. of Arkansas Fruit Substation, Clarksville. Damage was based on oxidative browning of the ovaries following an incubation period after removal from the freezer. With the exception of `Climax', a minimum temperature of –15C was required before bud damage was sufficient enough to differentiate among cultivars. All southern highbush cultivars and `Bluecrop' had superior hardiness compared to `Climax' at –15C in December, –20C in January, and –15C in February. Maximum hardiness of all cultivars was found in January. The hardier southern highbush cultivars were `Cape Fear' and `Blue Ridge'. Less hardy cultivars were `Gulf Coast, `Cooper', `Georgiagem', and `O'Neal', although the date of sampling affected the ranking of these clones for hardiness, especially for the February sample date. `Bluecrop' was not consistently hardier than the hardier southern highbush cultivars, except at the February sample date.

scholarly journals Flower Bud Density Affects Vegetative and Fruit Development in Field-grown Southern Highbush Blueberry

HortScience ◽  
1999 ◽  
Vol 34 (4) ◽  
pp. 607-610 ◽  
Author(s):  
B.E. Maust ◽  
J.G. Williamson ◽  
R.L. Darnell
Keyword(s):  
Leaf Area ◽  
Fruit Development ◽  
Fruit Size ◽  
Dry Weight ◽  
Vaccinium Corymbosum ◽  
Soluble Solids ◽  
Highbush Blueberry ◽  
Flower Buds ◽  
Flower Bud ◽  
Southern Highbush

Floral budbreak and fruit set in many southern highbush blueberry (SHB) cultivars (hybrids of Vaccinium corymbosum L. with other species of Vaccinium) begin prior to vegetative budbreak. Experiments were conducted with two SHB cultivars, `Misty' and `Sharpblue', to test the hypothesis that initial flower bud density (flower buds/m cane length) affects vegetative budbreak and shoot development, which in turn affect fruit development. Flower bud density of field-grown plants was adjusted in two nonconsecutive years by removing none, one-third, or two-thirds of the flower buds during dormancy. Vegetative budbreak, new shoot dry weight, leaf area, and leaf area: fruit ratios decreased with increasing flower bud density in both cultivars. Average fruit fresh weight and fruit soluble solids decreased in both cultivars, and fruit ripening was delayed in `Misty' as leaf area: fruit ratios decreased. This study indicates that because of the inverse relationship between flower bud density and canopy establishment, decreasing the density of flower buds in SHB will increase fruit size and quality and hasten ripening.

scholarly journals Flower Bud Load Influences Blueberry Vegetative and Fruit Development

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 682e-682
Author(s):  
B.E. Maust ◽  
J.G. Williamson ◽  
R.L. Darnell
Keyword(s):  
Leaf Area ◽  
Fruit Development ◽  
Reproductive Development ◽  
Dry Weight ◽  
Highbush Blueberry ◽  
Fresh Weight ◽  
Flower Buds ◽  
Flower Bud ◽  
Fruit Maturity ◽  
Southern Highbush

A field experiment was conducted in Gainesville, Fla., with two southern highbush blueberry cultivars, `Misty' and `Sharpblue', to investigate the influence of varying flower bud load on the timing and extent of vegetative and reproductive development. Flower bud load was adjusted on three different canes on ten plants by removing none, one-third, or two-thirds of the flower buds. Vegetative budbreak, leaf area, fruit number, and fruit fresh weight and dry weight were measured. Vegetative budbreak was delayed with increasing flower bud load. Vegetative budbreak, leaf area, and leaf area: fruit ratio decreased with increasing flower bud load. Fruit maturity was delayed and average berry fresh weight and dry weight declined with decreasing leaf area:fruit ratio. Responses were similar for both cultivars although `Misty' was more adversely affected by high flower bud load and low leaf area: fruit ratio.

scholarly journals 625 Early Fall Defoliation of Southern Highbush Blueberry Inhibits Flower Bud Initiation and Retards Flower Bud Development

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 505B-505 ◽  
Author(s):  
Jeffrey G. Williamson ◽  
E.P. Miller
Keyword(s):  
Unit Length ◽  
Highbush Blueberry ◽  
Similar Response ◽  
Block Designs ◽  
Flower Buds ◽  
Flower Bud ◽  
Bud Development ◽  
Early Fall ◽  
Southern Highbush ◽  
Flower Bud Development

In 1998, representative canes of mature, field-grown, `Misty' and `Sharpblue' southern highbush blueberry were hand-defoliated on 4 Sept., 2 Oct., 6 Nov., 7 Dec., or not defoliated. The experiment was repeated in 1999. Randomized complete-block designs with 11 (1998) or 10 (1999) replications were used. The early defoliation treatments (4 Sept. and 2 Oct.) resulted in reduced flower bud number per unit length of cane for `Misty', but not for `Sharpblue', when compared with later defoliation treatments or controls. A similar response to early defoliation was found both years for both cultivars. The later defoliation treatments (6 Nov. and 7 Dec.) had no significant effect on flower bud number compared to controls. Early defoliation had a negative effect on flower bud development for both cultivars. Flower buds that developed on canes defoliated on 4 Sept. or on 2 Oct. had smaller diameters than flower buds on canes defoliated on 6 Nov., 7 Dec., or on non-defoliated canes. Fruit fresh weight per unit cane length was less for the September and October defoliation treatments than for the December defoliation treatment or controls. These results support the need for summer pruning and a effective summer spray program to control leaf spot diseases that often result in early fall defoliation of southern highbush blueberries grown in the southeastern United States.

scholarly journals Flower and Fruit Load Influence Blueberry Plant Development and CO2 Exchange Rate

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 443A-443
Author(s):  
B.E. Maust ◽  
J.G. Williamson ◽  
R.L. Darnell
Keyword(s):  
Exchange Rate ◽  
Leaf Area ◽  
Fruit Ripening ◽  
Highbush Blueberry ◽  
Plant Canopy ◽  
Flower Buds ◽  
Flower Bud ◽  
Whole Plant ◽  
Southern Highbush ◽  
Fruit Load

Two southern highbush blueberry cultivars, `Sharpblue' and `Misty', were used to investigate the influence of varying flower bud density and fruit load on vegetative development, whole-plant canopy CO2 exchange rate (CER), and leaf CER. Plants were grown in pots and flower buds were removed so that initial flower bud density (fl ower bud number/total cane length) on a whole-plant basis ranged from 0.05–0.35 flower buds/cm. Vegetative budbreak number, leaf area, and leaf area: fruit ratio decreased with increasing flower bud density. In `Sharpblue', whole-plant canopy CER measured at fruit ripening decreased with increasing flower and fruit load and decreasing leaf area:fruit ratio, while leaf CER increased with increasing fruit load and decreasing leaf area:fruit ratio. In `Misty', whole-plant canopy CER measured 4 weeks after full bloom decreased with increasing flower and fruit load, but whole-plant canopy and leaf CER at fruit ripening were similar among the different fruit loads. Average fruit fresh and dry weights increased and the fruit development period decreased with increased leaf area:fruit ratio in both cultivars. These data suggest that carbohydrate source limitations from reduced leaf area development and whole-plant canopy CER lead to decreased fruit fresh and dry weights and delayed ripening in some southern highbush blueberry cultivars.

scholarly journals Effects of CPPU on Fruit Size, Set, and Yield of Southern Highbush Blueberry in Florida

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 793A-793
Author(s):  
Jeffrey G. Williamson* ◽  
E. Paul Miller
Keyword(s):  
Fruit Ripening ◽  
Fruit Set ◽  
Fruit Size ◽  
Vaccinium Corymbosum ◽  
Limiting Factors ◽  
Highbush Blueberry ◽  
Fresh Weight ◽  
Full Bloom ◽  
Berry Size ◽  
Southern Highbush

Poor fruit set and sub-optimum berry size are potential yield- and profit-limiting factors for southern highbush (Vaccinium corymbosum) blueberry production in Florida. The cytokinin N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) has increased fruit size and fruit set of a number of fruit crops including rabbiteye blueberry. The purpose of this study was to determine the effects of CPPU applied at different rates and phenological stages of bloom and/or fruit development on fruit size, set, and yield of southern highbush blueberry. `Millennia' and `Star' southern highbush blueberry plants located on a commercial blueberry farm in Alachua County, Fla., were treated with 5 or 10 ppm CPPU at various stages of development ranging from full bloom to 20 days after full bloom. In contrast to findings with rabbiteye blueberry, fruit set in this study of southern highbush blueberry was not affected by any of the CPPU treatments when compared to the controls. Nor was total fruit yield affected by CPPU treatments. The most noticeable potential benefit found in this study was an increase in mean fruit fresh weight from CPPU treatments. However, cultivars responded differently to CPPU with respect to mean fruit fresh weight. For `Millennia', only one CPPU treatment increased mean fruit weight compared to controls. However, for `Star', all but one CPPU treatment increased mean fruit fresh weight. Several CPPU treatments resulted in delayed fruit ripening for `Star' but not for `Millennia'. For `Star', the treatments that most consistently delayed fruit ripening tended to have greater fruit fresh weights.

scholarly journals Cold Injury of Southern Blueberries as a Function of Germplasm and Season of Flower Bud Development

HortScience ◽  
1991 ◽  
Vol 26 (1) ◽  
pp. 18-20 ◽  
Author(s):  
Kim Patten ◽  
Elizabeth Neuendorff ◽  
Gary Nimr ◽  
John R. Clark ◽  
Gina Fernandez
Keyword(s):  
Frost Damage ◽  
Vaccinium Corymbosum ◽  
Highbush Blueberry ◽  
Flower Buds ◽  
Flower Bud ◽  
Bud Development ◽  
Stage Of Development ◽  
Cold Damage ◽  
Southern Highbush ◽  
Flower Bud Development

The relative tolerance of flower buds and flowers of southern highbush blueberry (Vaccinium spp.) to cold damage was compared to rabbiteye (Vaccinium ashei Reade) and highbush blueberry (Vaccinium corymbosum L.). For similar stages of floral bud development, southern highbush and highbush cultivars had less winter freeze and spring frost damage than rabbiteye cultivars. Cold damage increased linearly with stage of flower bud development. Small fruit were more sensitive to frost damage than open flowers. Rabbiteye blueberry flower buds formed during the fall growth flush were more hardy than buds formed during the spring growth flush, regardless of cultivar or stage of development.

Hydrogen Cyanamide Increases Leafing and Reduces Fruit Development Period of Southern Highbush Blueberry

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 529c-529
Author(s):  
J.G. Williamson ◽  
B.E. Maust ◽  
R.L. Darnell
Keyword(s):  
Fruit Development ◽  
Fruit Size ◽  
Highbush Blueberry ◽  
Flower Bud ◽  
North Central ◽  
Hydrogen Cyanamide ◽  
Central Florida ◽  
Fruit Thinning ◽  
Fruit Maturity ◽  
Southern Highbush

Mature, field-grown `Misty' southern highbush blueberry plants were sprayed to drip with 0, 20.4, and 10.2 g·L–1 concentrations of hydrogen cyanamide in north-central Florida on 20 Dec. and 7 Jan. 1996–97. Plants were dormant and leafless, with slightly swollen flower buds, at the time of spray applications. All hydrogen cyanamide sprays increased the extent and earliness of vegetative budbreak and canopy establishment. The number of vegetative budbreaks per centimeter of shoot length increased linearly with increasing spray concentration of hydrogen cyanamide. Hydrogen cyanamide-treated fruit had greater average fresh weights and shorter average fruit development periods than non-treated fruit. On 15 Apr., 40% ti 60% of hydrogen cyanamide-treated fruit were ripe compared to about 10% of control fruit. Some flower bud damage and subsequent fruit thinning was observed from the 20.4 g·L–1 spray, especially at the later spray date. Hydrogen cyanamide shows potential for increasing early fruit maturity and fruit size of some southern highbush blueberry cultivars in Florida.

scholarly journals Reproductive Development in Evergreen vs. Deciduous Blueberry Production System

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 443D-443
Author(s):  
Peter A.W. Swain ◽  
Rebecca L. Darnell
Keyword(s):  
Production System ◽  
Reproductive Development ◽  
Vaccinium Corymbosum ◽  
N Fertilization ◽  
Highbush Blueberry ◽  
Fresh Weight ◽  
Flower Buds ◽  
Flower Bud ◽  
Active Growth ◽  
Southern Highbush

Two cultivars of southern highbush blueberry (Vaccinium corymbosum interspecific hybrid) were grown in containers under the traditional deciduous production system, or the dormancy-avoiding evergreen production system. In the dormancy-avoiding system, plants are maintained evergreen and do not enter dormancy in the winter. This alleviates the chilling requirement, thus extending the potential growing area of blueberries into subtropical regions. Plants in the evergreen production system were maintained in active growth through weekly or biweekly N fertilization (≈21–23 g N/ plant per year). Keeping foliage through the year lengthens the duration of the photosynthetic season of the plant and is hypothesized to improve the carbohydrate (CHO) status of the evergreen plants. This, in turn, may decrease source limitations to reproductive development and potentially increase fruit number and/or size. In both cultivars, the evergreen production system advanced the time of anthesis by 3 to 4 weeks compared to the deciduous production system. Plants in the evergreen system initiated 10% to 25% more flower buds than plants in the deciduous system, depending on cultivar. Average leaf area, leaf fresh weight, total above-ground fresh weight, bud density, and cane length were greater in the evergreen plants than deciduous. The evergreen production system increased plant fresh weight and flower bud number compared to the deciduous system, and may ultimately increase yield.

scholarly journals Carbohydrate Reserve Concentrations and Flower Bud Density Effects on Vegetative and Reproductive Development in Southern Highbush Blueberry

2000 ◽  
Vol 125 (4) ◽  
pp. 413-419 ◽  
Author(s):  
B.E. Maust ◽  
J.G. Williamson ◽  
R.L. Darnell
Keyword(s):  
Leaf Area ◽  
Vegetative Growth ◽  
Fruit Size ◽  
Reproductive Development ◽  
Highbush Blueberry ◽  
Flower Bud ◽  
Vegetative Development ◽  
Carbohydrate Reserves ◽  
Carbohydrate Reserve ◽  
Southern Highbush

Vegetative budbreak, leaf area development, and fruit size in southern highbush blueberry (Vaccinium corymbosum L. interspecific hybrids) decrease as flower bud density increases. The effect on fruit size has been attributed to both insufficient carbohydrate reserves and reductions in current photoassimilates caused by decreased vegetative growth. Experiments were conducted with two southern highbush blueberry cultivars, `Misty' and `Sharpblue', to test the hypothesis that increased carbohydrate reserve concentrations can overcome the detrimental effects of high flower bud density by increasing vegetative budbreak, shoot development, and whole-canopy net CO2 exchange rate (NCER), which in turn will increase fruit size. Fully foliated plants were placed in greenhouses with either ambient (AMB) CO2 levels (≈360 μmol·mol-1) or enriched (ENR) CO2 levels (≈700 μmol·mol-1) for 38 d during fall. Plants were then moved outdoors, hand defoliated, and flower bud density (flower buds/cm cane length) adjusted to range from 0.07 to 0.31. Root starch and whole plant carbohydrate concentrations increased in ENR compared with AMB plants of both cultivars. Vegetative budbreak (number per centimeter cane length), leaf area, and whole-canopy NCER decreased as flower bud density increased in AMB and ENR plants of both cultivars; however, ENR `Sharpblue' plants had significantly greater vegetative growth and wholecanopy NCER at a given flower bud density compared with AMB `Sharpblue'. Concomitant with this was an increase in fruit fresh weight in ENR compared to AMB `Sharpblue'. This was not the case with `Misty', where vegetative development and fruit size were similar in ENR and AMB plants. Thus, the hypothesis that increased carbohydrate reserves will increase vegetative development and subsequent fruit size may be true only in certain cultivars of southern highbush blueberry. Alternatively, the increased carbohydrate reserve concentrations in ENR compared with AMB `Misty' plants may have been insufficient to affect subsequent vegetative or reproductive development.

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