scholarly journals Early and Mid-fall Defoliation Reduces Flower Bud Number and Yield of Southern Highbush Blueberry

2002 ◽  
Vol 12 (2) ◽  
pp. 214-216 ◽  
Author(s):  
J.G. Williamson ◽  
E.P. Miller
Keyword(s):  
Fruit Set ◽  
Vaccinium Corymbosum ◽  
Fruit Yield ◽  
Negative Effects ◽  
Flower Bud ◽  
Experiment Control ◽  
Early Fall ◽  
Southern Highbush ◽  
High Yields ◽  
Bud Initiation

Three experiments were conducted in north-central Florida to determine the effects of fall defoliation on flower bud initiation and yield of southern highbush (SHB) blueberry (Vaccinium corymbosum hybrid). In 1998, randomly selected upright shoots of mature, field-grown `Misty' and `Sharpblue' plants were hand-defoliated at monthly intervals beginning 4 Sept. and ending 7 Dec. In 1999, a similar study was conducted using different plants of the same cultivars. Representative shoots were defoliated at monthly intervals beginning 14 Sept. and ending 15 Dec. Additional shoots were also partially defoliated by removing the distal two-thirds of each leaf at monthly intervals from 15 Oct. through 15 Dec. In a third experiment, 2-year-old container-grown `Star' SHB plants were completely defoliated at monthly intervals beginning 13 Sept. and ending 15 Dec. In each experiment, control shoots, or plants ('Star'), were not defoliated. Although there were differences among cultivars and years, all cultivars tested demonstrated negative effects on reproductive growth and development from September and October defoliations. For `Sharpblue', reduced fruit yield from early fall defoliation appeared to be due to fewer fruit set per flower bud. However, for `Misty', reduced fruit yield from early fall defoliation was the result of large reductions in flower bud numbers as well as fewer fruit set per flower bud. September and October defoliations of `Star' reduced yields or delayed fruit ripening. Collectively, these experiments demonstrate the importance of maintaining healthy foliage through October in the lower southeastern United States for adequate flower bud initiation and high yields of SHB blueberry the following spring.

scholarly journals Photoperiod and Temperature Effects on Growth and Carbohydrate Storage in Southern Highbush Blueberry Interspecific Hybrid

2004 ◽  
Vol 129 (3) ◽  
pp. 294-298 ◽  
Author(s):  
Timothy M. Spann ◽  
Jeffrey G. Williamson ◽  
Rebecca L. Darnell
Keyword(s):  
High Temperature ◽  
Interspecific Hybrid ◽  
Vaccinium Corymbosum ◽  
Highbush Blueberry ◽  
Flower Bud ◽  
Experimental Conditions ◽  
Carbohydrate Concentration ◽  
Southern Highbush ◽  
Bud Initiation ◽  
Carbohydrate Status

Experiments were conducted with `Misty' southern highbush blueberry (Vaccinium corymbosum L. interspecific hybrid) to test the effects of high temperature on flower bud initiation and carbohydrate accumulation and partitioning. Plants were grown under inductive short days (SDs = 8 hour photoperiod) or noninductive SDs with night interrupt (SD-NI = 8 hour photoperiod + 1 hour night interrupt), at either 21 or 28 °C for either 4 or 8 weeks. Flower bud initiation occurred only in the inductive SD treatments and was significantly reduced at 28 °C compared with 21 °C. The number of flower buds initiated was not significantly different between 4- and 8-week durations within the inductive SD, 21 °C treatment. However, floral differentiation appeared to be incomplete in the 4-week duration buds and bloom was delayed and reduced. Although plant carbohydrate status was not associated with differences in flower bud initiation between SD and SD-NI treatments, within SD plants, decreased flower bud initiation at high temperature was correlated with decreased whole-plant carbohydrate concentration. These data indicate that flower bud initiation in southern highbush blueberry is a SD/long night phytochrome-mediated response, and plant carbohydrate status plays little, if any, role in regulating initiation under these experimental conditions.

scholarly journals Inflorescence Bud Initiation, Development, and Bloom in Two Southern Highbush Blueberry Cultivars

2015 ◽  
Vol 140 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Alisson P. Kovaleski ◽  
Jeffrey G. Williamson ◽  
James W. Olmstead ◽  
Rebecca L. Darnell
Keyword(s):  
Interspecific Hybrids ◽  
Shoot Growth ◽  
Late Summer ◽  
Vaccinium Corymbosum ◽  
Highbush Blueberry ◽  
Bud Development ◽  
Late Fall ◽  
Southern Highbush ◽  
Bud Initiation ◽  
The Relationship

Blueberry (Vaccinium spp.) production is increasing worldwide, particularly in subtropical growing regions, but information on timing and extent of inflorescence bud development during summer and fall and effects on bloom the next season are limited. The objectives of this study were to determine time of inflorescence bud initiation, describe internal inflorescence bud development, and determine the relationship between internal inflorescence bud development and bloom period the next spring in two southern highbush blueberry [SHB (Vaccinium corymbosum interspecific hybrids)] cultivars. ‘Emerald’ and ‘Jewel’ SHB buds were collected beginning in late summer until shoot growth cessation in late fall for dissection and identification of organ development. Inflorescence bud frequency and number, vegetative and inflorescence bud length and width throughout development, and bloom were also assessed. Inflorescence bud initiation occurred earlier in ‘Emerald’ compared with ‘Jewel’. Five stages of internal inflorescence bud development were defined throughout fall in both cultivars, ranging from a vegetative meristem to early expansion of the inflorescence bud in late fall. ‘Emerald’ inflorescence buds were larger and bloomed earlier, reflecting the earlier inflorescence bud initiation and development. Although inflorescence bud initiation occurred earlier in ‘Emerald’ compared with ‘Jewel’, the pattern of development was not different. Timing of inflorescence bud initiation influenced timing of bloom with earlier initiation resulting in earlier bloom.

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 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 Cold Hardiness and Options for the Freeze Protection of Southern Highbush Blueberry

Agriculture ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 9 ◽  
Author(s):  
Erick D. Smith
Keyword(s):  
Cold Hardiness ◽  
Fruit Set ◽  
Vaccinium Corymbosum ◽  
Early Spring ◽  
Climatic Conditions ◽  
Critical Temperatures ◽  
Overhead Irrigation ◽  
Frost Protection ◽  
Southern Highbush ◽  
Freeze Protection

Southern highbush blueberries (SHB; Vaccinium corymbosum interspecific hybrid) are a low chill species of blueberry that are commercially grown in sub-tropical climates. Due to the nature of SHB, the flowering and fruit set occur in mid-winter to early spring and are susceptible to freeze damage. The most effective use of freeze protection is based on climatic conditions. Identification of advective or radiative freeze, intensity of the freeze event, and the equipment deployed are the key elements for deciding if the crop can be protected and justifying the expense to operate the system. Of the various methods used in frost protection, applying overhead irrigation water is the most promising. During a freeze event, an application of 6.3 mm ha−1 (0.10 in A−1) of water per hour is required to protect blueberries from −2.8 °C (27 °F) temperature with winds from 0 to 16 km h−1 (0 to 10 mph). This is 25.4 kL h−1 ha−1 (2715 gal h−1 A−1) of water. Overhead irrigation freeze protection is dependent on large volumes of water. This paper will review methods of freeze/frost protection, importance of weather patterns, and critical temperatures based on phenology of flowering to fruit set.

scholarly journals Optimizing Nitrogen Fertigation Rates for Young Southern Highbush Blueberry

Agronomy ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 389
Author(s):  
Yang Fang ◽  
Jeffrey Williamson ◽  
Rebecca Darnell ◽  
Yuncong Li ◽  
Guodong Liu
Keyword(s):  
Fruit Quality ◽  
Ground Cover ◽  
Vaccinium Corymbosum ◽  
Fruit Yield ◽  
Growth And Yield ◽  
Nutrient Concentrations ◽  
Highbush Blueberry ◽  
Soil Nitrate ◽  
Southern Highbush ◽  
N Rates

The commercial blueberry industry in Florida has expanded significantly in both acreage and value in the past several years. The southern highbush blueberry (SHB, Vaccinium corymbosum L. interspecific hybrid) is the major blueberry type grown in Florida. The nitrogen (N) demand of young SHB differs from the northern highbush blueberry (NHB, V. corymbosum L.) and from mature blueberry plants. The objective of this study was to optimize fertigated N rates for the growth and yield of young SHB plants. One-year-old ‘Emerald’ and ‘Farthing’ plants were fertilized with 32N-0P-0K through drip irrigation at annual rates of 0, 42, 84, 168, and 336 kg N ha−1. Soil nitrate levels at multiple depths were measured along with leaf nutrient concentration, percent canopy ground cover, fruit yield and fruit quality. The results indicated that N rates had no significant effect on leaf nutrient concentrations. Greater N rates advanced bloom and harvest, increased percentage of ground cover (an indicator of canopy size), fruit yield and berry numbers per plant, but decreased mean berry diameter and weight. The soil nitrate results from both ‘Emerald’ and ‘Farthing’ revealed that the 336 kg N ha−1 treatment had a significantly greater risk for nitrate leaching than the lower N treatments in spring. The effect of N rates on fruit quality varied with cultivar and harvest season. The linear plateau regression of fruit yield and N rates indicated that the maximum yield reached at the annual N fertigation rate of 222 kg ha−1 for ‘Emerald’ and 206 kg ha−1 for ‘Farthing’.

scholarly journals 526 Hydrogen Cyanamide Hastens Fruit Development and Increases Fruit Yield and Berry Size of Blueberry

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 536C-536
Author(s):  
J.G. Williamson ◽  
E.P. Miller
Keyword(s):  
Fruit Development ◽  
Fruit Yield ◽  
Yield Response ◽  
Flower Bud ◽  
North Central ◽  
Hydrogen Cyanamide ◽  
Central Florida ◽  
Berry Size ◽  
Southern Highbush ◽  
The Times

Field-grown `Misty', `Star', and `Southmoon' southern highbush, and `Climax' rabbiteye blueberry plants were sprayed to drip with 0, 7.7 and 15.4 g·L–1 concentrations of hydrogen cyanamide in north central Florida on 17 Dec. 1997 and 6 Jan. 1998. Plants were dormant with slightly swollen flower buds (stage 2) at the times of applications. The extent and earliness of vegetative budbreak were increased by both hydrogen cyanamide sprays. Hydrogen cyanamide also increased mean fruit fresh weights and reduced fruit development periods for `Misty', `Southmoon' and `Climax' but not for `Star'. Yield response to hydrogen cyanamide was variable among cultivars. Fruit yields of `Misty' and `Climax' increased slightly by 7.7 g·L–1 sprays and decreased significantly by 15.4 g·L–1 sprays. In that case, increased fruit yields appeared to be the result of greater mean fruit fresh weights while reduced yields resulted from significant flower bud thinning that occurred at the highest spray concentration. Both hydrogen cyanamide spray concentrations increased fruit yield for `Southmoon' and decreased fruit yield for `Star' when compared to controls. Spray date had no effect on fruit yield and little effect on fruit development period. Hydrogen cyanamide has potential for increasing fruit quality and earliness of some blueberry cultivars that are grown in the lower southeastern United States.

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 Effects of CPPU Applications on Southern Highbush Blueberries

HortScience ◽  
2007 ◽  
Vol 42 (7) ◽  
pp. 1612-1615 ◽  
Author(s):  
Jeffrey G. Williamson ◽  
D. Scott NeSmith
Keyword(s):  
Growth Regulator ◽  
Field Experiments ◽  
Fruit Set ◽  
Vaccinium Corymbosum ◽  
Highbush Blueberry ◽  
Berry Size ◽  
Spray Volume ◽  
Highbush Blueberries ◽  
Southern Highbush ◽  
Spray Timing

Greenhouse and field experiments were conducted to determine the effects of the growth regulator N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) on fruit set, berry size, and yield of southern highbush blueberry (Vaccinium corymbosum hybrids). The experiments were conducted over a period of several years in Georgia and Florida. CPPU sprays were capable of increasing fruit set and berry weight of southern highbush blueberry, although the responses to CPPU treatment were variable and appeared to be influenced by factors such as rate, spray timing, and cultivar. In Florida, high natural fruit set may have prevented increased fruit set from CPPU. A slight delay in berry maturity was noted in several experiments. Spray burn occurred on several occasions and may be related to factors such as cultivar, rate, spray volume, and use of surfactant.

scholarly journals Differences in Phenology and Reserve Carbohydrate Concentrations Between Dormant and Nondormant Production Systems in Southern Highbush Blueberry

2001 ◽  
Vol 126 (4) ◽  
pp. 386-393 ◽  
Author(s):  
P.A.W. Swain ◽  
R.L. Darnell
Keyword(s):  
Production Systems ◽  
Vaccinium Corymbosum ◽  
N Fertilization ◽  
Highbush Blueberry ◽  
Flower Bud ◽  
Vegetative Development ◽  
Average Maximum ◽  
Leaf Retention ◽  
Southern Highbush ◽  
Reserve Carbohydrate

Two cultivars of southern highbush blueberry (Vaccinium corymbosum L. interspecific hybrid), `Sharpblue' and `Wannabe', were container-grown outside in either a dormant or nondormant production system to determine how the two production systems affected carbohydrate (CH2O) status, growth, and development. Plants were maintained in the nondormant condition by continuous N fertilization throughout winter (average maximum/minimum temperatures of 17/5 °C). Plants in the nondormant system retained their foliage longer into the winter compared with plants in the dormant system. Flower bud number, density, fruit number, and total fruit fresh weight (FW) per plant were greater in the nondormant compared with the dormant system plants for both cultivars. Mean fruit FW was greater in dormant compared with nondormant `Wannabe' plants, while in `Sharpblue', mean fruit FW was similar in both systems. Cane and root CH2O concentrations in nondormant system plants were generally similar to or lower than those measured in dormant system plants. Assuming that longer leaf retention in nondormant system plants increased CH2O synthesis compared with dormant system plants, the patterns of reproductive/vegetative development and root/shoot CH2O concentrations indicate that the increased CH2O in nondormant system plants was allocated to increased reproductive growth in lieu of CH2O reserve accumulation. It is probable that this increased CH2O availability, combined with longer perception of short days due to longer leaf retention, were major factors in increasing flower bud initiation and yield in the nondormant compared with the dormant system plants.

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