scholarly journals Response of Rabbiteye Blueberry (Vaccinium ashei Reade) to the Growth Regulators CPPU and Gibberellic Acid

HortScience ◽  
2002 ◽  
Vol 37 (4) ◽  
pp. 666-668 ◽  
Author(s):  
D. Scott NeSmith
Keyword(s):  
Gibberellic Acid ◽  
Growth Regulator ◽  
Fruit Set ◽  
Total Yield ◽  
Control Treatment ◽  
Single Application ◽  
Treatment Results ◽  
Vaccinium Ashei ◽  
Berry Size ◽  
Mature Field

Experiments were conducted during 1999 and 2000 at Griffin, Ga., with rabbiteye blueberries (Vaccinium ashei Reade) to determine how the growth regulator CPPU affected fruit set, berry size, and yield. CPPU (applied at two different timings) was used alone, and in conjunction with GA3 on mature, field-grown `Tifblue' plants. A control treatment without either growth regulator was also included. The CPPU concentration used was 10 mg·L-1 (a single application per treatment), and the GA3 concentration used was 200 mg·L-1 (two applications per treatment). Results from both years showed a positive benefit of CPPU with respect to fruit set and berry size, especially in the absence of GA3. Depending on timing, berry number per plant was increased by more than 200% in 1999 using CPPU. Berry size increases of more than 30% occurred in 2000 when CPPU alone was applied at 17 d after flowering (DAF). CPPU did not increase berry size of GA3-treated plants in either year. Total yield per plant during 2000 was 5.0, 7.1, and 8.3 kg for control, CPPU applied 7 DAF, and CPPU applied 17 DAF treatments, respectively, without GA3. While CPPU did substantially increase fruit set, berry size, and yield of `Tifblue', there was a notable delay in fruit ripening. These results suggest that CPPU may be useful for increasing yield of rabbiteye blueberries under conditions of inadequate fruit set (such as occurs in much of the Southeast), but a delay in ripening will likely result. Chemical names used: N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU); gibberellic acid (GA3).

scholarly journals Flower Bud Stage and Chill Hours Influence the Activity of GA3 Applied to Rabbiteye Blueberry

HortScience ◽  
1992 ◽  
Vol 27 (4) ◽  
pp. 316-318 ◽  
Author(s):  
D.S. NeSmith ◽  
Gerard Krewer
Keyword(s):  
Gibberellic Acid ◽  
Growth Regulator ◽  
Flower Development ◽  
Fruit Set ◽  
Developmental Stages ◽  
Single Application ◽  
Flower Buds ◽  
Flower Bud ◽  
Vaccinium Ashei

Individual flower clusters of `Tifblue' rabbiteye blueberry (Vaccinium ashei Reade) were treated with 300 ppm GA at several flower bud stages to determine the activity of the growth regulator in promoting fruit set. Applications were made one time only at a specified stage of flower development, or once followed by a second application. A single application of GA when flower buds had elongated but corollas had not expanded (stage 5) led to the largest increase in fruit set. Two applications of GA, 10 to 18 days apart, increased fruit set compared with a single application at flower developmental stages other than stage 5. Fruit set promoted by a single spray of GA imposed on fully expanded corollas (stage 6) decreased with increasing number of chill hours (350, 520, 760, or 1150). Chemical names used: gibberellic acid (GA).

scholarly journals Effects of Timing of CPPU Applications on Rabbiteye Blueberries

HortScience ◽  
2008 ◽  
Vol 43 (5) ◽  
pp. 1446-1448 ◽  
Author(s):  
D. Scott NeSmith
Keyword(s):  
Growth Regulators ◽  
Growth Regulator ◽  
Fruit Set ◽  
Positive Response ◽  
Vaccinium Ashei ◽  
Desirable Response ◽  
Greenhouse Experiments ◽  
Berry Size

A series of field and greenhouse experiments were conducted at two locations in Georgia to determine how rabbiteye blueberries (Vaccinium ashei Reade) respond to different timings of application of the growth regulator [N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU)]. In all tests, a CPPU rate of 15 mg·L−1 was used, and timings of applications were based on days after flowering (DAF). Overall, results indicate that a positive response in fruit set or berry size can occur with applications of CPPU depending on cultivar and timing of application. As with many growth regulators, the effect can vary, and these experiments indicate that the timing of CPPU application is critical in achieving the most desirable response. Collectively, data suggest an optimum window of application of CPPU to rabbiteye blueberries is between 7 and 21 DAF with the most probable success being from an application made around 14 ± 3 DAF.

scholarly journals Gibberellic Acid Applied at Bloom Reduces Fruit Set and Improves Size of 'Crimson Seedless' Table Grapes

HortScience ◽  
2001 ◽  
Vol 36 (4) ◽  
pp. 706-709 ◽  
Author(s):  
N.K. Dokoozlian ◽  
W.L. Peacock
Keyword(s):  
Gibberellic Acid ◽  
Fruit Set ◽  
Single Application ◽  
Full Bloom ◽  
Cluster Number ◽  
Application Timing ◽  
Table Grapes ◽  
Berry Size ◽  
Bunch Rot

Excessive fruit set can reduce the quality of 'Crimson Seedless' table grapes (Vitis vinifera L.), resulting in compact, tightly filled clusters with small berries that are prone to bunch rot at harvest. Two separate studies were conducted to examine the effects of application timing and rate on the efficacy of GA3 for berry thinning. In the first experiment, vines were treated with 2 g·ha-1 GA3 at one of the following stages of bloom: 1% to 5%; 20% to 30%; 50% to 60%; 80% to 90%; or 100% capfall (falling of the calyptra). The second experiment compared treatments of 0, 2.5, 6.25, 12.5, 18.75, or 25 g·ha-1 GA3 applied at ≈80% bloom. Fruit set (number of berries/cm shoulder length) was similar among vines treated between 1% to 5% and 100% bloom with 2 g·ha-1 GA3, although berry set was reduced relative to the control. However, applications made during the later stages of bloom significantly increased berry length and weight. Fruit set generally declined, and the number of shot berries per cluster increased, as the amount of GA3 applied at bloom increased. Applications ≥6.25 g·ha-1 GA3 resulted in commercially unacceptable levels of shot berries, as well as significant reductions in cluster weight and packable yield per vine. The results indicate that a single application of 2.5 g·ha-1 GA3 near full bloom may be used to reduce fruit set and increase berry size of this cultivar without detrimental effects on packable yield or cluster number per vine the subsequent year. Chemical name used: gibberellic acid (GA3).

scholarly journals 300 Effects of Plant Growth Regulators on Eggplant (Solanum melongena L.) Yield

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 443C-443
Author(s):  
J. Pablo Morales-Payan
Keyword(s):  
Plant Growth ◽  
Gibberellic Acid ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Fruit Set ◽  
Block Design ◽  
Control Treatment ◽  
Amine Hydrochloride ◽  
Yield Increase ◽  
Giberellic Acid

Field studies were conducted in the Dominican Republic to determine the effect of several plant growth regulators on the yield of `Jira' eggplant. Treatments consisted of aqueous solutions of folcysteine (25, 50, 75 ppm), giberellic acid 3 (10, 20, 30 ppm), kinetine (25, 50, 75 ppm), naphthalenacetic acid (NAA) (25, 50, 75 ppm), 2,3,4-dichloro-phenoxy-triethyl-amine hydrochloride (DCPTA) (25, 50, 75 ppm), triacontanol (5, 10, 15 ppm), ethanol (5, 10, 15%), and chlormequat (50, 100, 150 ppm) sprayed at early flowering, directed to the crop upper leaves and flowers. A control treatment (no plant growth regulators applied) was also included. A randomized complete-block design with four replications was utilized. Experimental units were two rows of 10 plants at a 1.0 × 0.4-m distancing. Eggplant fruit set and yield were determined after 10 harvests performed at 3-day intervals. Analysis of variance and mean comparison tests were performed on the resulting data. `Jira' eggplant fruit set and yield was significantly improved by folcysteine, giberellic acid 3, and NAA, but not by kinetine, DCPTA, ethanol, triacontanol, or chlormequat. Eggplant yield increased as folcysteine rate increased from 0 to 50 ppm, but no further yield increase was obtained when increasing the rate from 50 to 75 ppm. Similarly, eggplant yield significantly increased as gibberellic acid increased from 0 to 20 ppm, but not when rates increased from 20 to 30 ppm. With NAA, eggplant fruit set and yield significantly increased above that of control plants when 25 ppm was applied, with no significant yield increase at higher rates. Results indicate that the yield of `Jira' eggplants could be enhanced by the treatments with either folcysteine, NAA, or gibberellic acid hereby described.

scholarly journals Gibberellic Acid-induced Fruit Set of Rabbiteye Blueberry following Freeze and Physical Injury

HortScience ◽  
1995 ◽  
Vol 30 (6) ◽  
pp. 1241-1243 ◽  
Author(s):  
D. Scott NeSmith ◽  
Gerard Krewer ◽  
Mark Rieger ◽  
Ben Mullinix
Keyword(s):  
Gibberellic Acid ◽  
Field Experiments ◽  
Fruit Set ◽  
Field Trials ◽  
Fruit Weight ◽  
Physical Injury ◽  
Vaccinium Ashei ◽  
Freeze Injury ◽  
Green House ◽  
Series Of Experiments

In a series of experiments, gibberellic acid (GA3) was applied to rabbiteye blueberries (Vaccinium ashei Reade) under field and greenhouse conditions to determine if fruit set could be improved following physical or freeze injury to flowers. In field experiments, physically damaged flowers (i.e., corollas and styles removed, styles only removed, or ovaries lanced) of `Climax' and `Tifblue' treated with GA3 (4% ProGib at 250 mg·liter–1) set substantially more fruit than nontreated, damaged flowers. Under green-house conditions, GA3 applied postfreeze to `Tifblue' and `Brightwell' resulted in increased fruit set compared to unsprayed control plants of the same cultivars. Freeze-damaged plants had substantially reduced fruit set overall but to a much lesser extent for GA3-treated plants than for those not treated with GA3. Individual fruit weight was reduced by GA3 applications, as was berry seediness. Results from these greenhouse and field trials suggest that GA3 can be used to salvage a blueberry crop following a moderate freeze during bloom.

Effects of growth regulators and bunch trimming on size, maturity and yield of sultana grapes

1970 ◽  
Vol 10 (45) ◽  
pp. 474 ◽  
Author(s):  
RS Sproule ◽  
MC Stannard
Keyword(s):  
Gibberellic Acid ◽  
Growth Regulators ◽  
Total Yield ◽  
Fresh Fruit ◽  
Full Bloom ◽  
Berry Size ◽  
Normal Shape ◽  
Berry Set

Three experiments were done over two seasons on the effect of gibberellic acid (GA) and parachlorophenoxyacetic acid (PCPA) sprays and bunch trimming on the yield, berry characters, maturity, and bunch quality of sultanas. GA applied at the shatter stage at 10 p.p.m. increased berry size and bunch quality of fresh fruit. When applied at full bloom, berry size was increased and earlier maturity was induced but berry set and yield were reduced. If applied at commencement of bloom. GA caused considerable thinning and the bunches were unattractive. Splitting the application into two 5 p.p.m. applications at commencement and full bloom was also unsatisfactory. A combined spray of PCPA and GA at shatter stage retarded maturity but increased berry size and yield over GA alone. It was shown that PCPA should be applied separately several days after shatter to avoid retention of shoe bellies. GA increased berry size mainly by elongation. Addition of PCPA produced larger berries of more normal shape. Bunch trimming decreased total yield of most treatments, but did not increase quantity of marketable fresh fruit. However, in general, berry length, diameter, and weight were increased by trimming. The importance of thorough wetting of the bunches by gibberellic acid sprays was demonstrated in a dipping experiment.

SOME CLUSTER THINNING AND GIBBERELLIC ACID EFFECTS ON FRUIT SET, BERRY SIZE, VINE GROWTH AND YIELD OF DE CHAUNAC GRAPES

1977 ◽  
Vol 57 (3) ◽  
pp. 653-659 ◽  
Author(s):  
N. E. LOONEY ◽  
D. F. WOOD
Keyword(s):  
Gibberellic Acid ◽  
Fruit Set ◽  
Growth And Yield ◽  
Vine Growth ◽  
Berry Weight ◽  
Berry Size ◽  
Cluster Thinning ◽  
Berry Set

De Chaunac grapes were thinned to one- and two-flower clusters per fruitful shoot, cluster-pruned by removing part of the flower cluster of two clusters per shoot and/or sprayed with 50 ppm gibberellic acid (GA3) 10 days after bloom. A low to moderate vigor vineyard was treated in 1974 and a high vigor vineyard treated in 1975. GA3 enhanced berry weight in both trials, the greatest effect being on berries in more distal clusters. GA3 did not affect berry set. Thinning to one cluster reduced yield in both tests. Thinning to two clusters coupled with cluster pruning reduced yield in the high vigor block. Berry set was enhanced by thinning to one cluster in the vigorous block and by cluster pruning in both trials. Individual berry weight was increased by thinning in 1974 and by thinning plus GA3 in 1975. Thinning to one cluster coupled with GA3 treatment increased vine growth in both experiments.

scholarly journals Osmia lignaria (Hymenoptera: Megachilidae) produce larger and heavier blueberries than honey bees (Hymenoptera: Apidae)

2020 ◽  
Author(s):  
Christine Cairns Fortuin ◽  
Kamal JK Gandhi
Keyword(s):  
Apis Mellifera ◽  
Honey Bees ◽  
Fruit Set ◽  
Solitary Bee ◽  
Field Cage ◽  
Vaccinium Ashei ◽  
Osmia Lignaria ◽  
Berry Weight ◽  
Berry Size

AbstractFruit set, berry size, and berry weight were assessed for pollination by the solitary bee Osmia lignaria (Say) in caged rabbiteye blueberries (Vaccinium ashei Reade, Ericales : Ericaceae), and compared to that of uncaged rabbiteye blueberries which were pollinated largely by honey bees (Apis mellifera L). O. linaria produced berries that were 1.6mm larger in diameter and 0.45g heavier than uncaged blueberries. Fruit set was 40% higher in uncaged blueberries. This suggests that Osmia bees can produce larger and heavier berry fruit, but O. lignaria may be less efficient at blueberry pollination as compared to A. mellifera under field cage conditions.

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 Salvaging a Rabbiteye Blueberry Crop with GA3 following Sub-freezing Temperatures

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 575d-575
Author(s):  
D. Scott NeSmith ◽  
Gerard Krewer ◽  
Orville Lindstrom
Keyword(s):  
Gibberellic Acid ◽  
Cold Exposure ◽  
Fruit Set ◽  
Temperature Limit ◽  
Flower Buds ◽  
Vaccinium Ashei ◽  
Growth Chambers ◽  
Freezing Temperatures ◽  
Flower Damage

Recent research in Georgia indicated gibberellic acid (GA3) could possibly be used to induce fruit set of freeze damaged rabbiteye blueberry (Vaccinium ashei) blooms. This research was conducted to determine the subfreezing temperature limit at which GA3 could be expected to be of use in salvaging a crop with freeze-damaged flowers. Rabbiteye blueberries with flower buds at stages 5 to 6 of development (fully elongated corollas and open blooms) were exposed to temperatures of 0, –1, –3, and –4.5°C in growth chambers to simulate overnight freezing events. After cold exposure, plants were placed in a greenhouse with a hive of bumblebees. Half of the plants were treated with GA3 and half were not. The number of flowers and subsequent fruit were recorded in order to calculate fruit set. Temperatures of –1°C and below caused fruit set resulting from pollination by bees to decline compared to control plants; whereas, flowers treated with GA3 had fruit set comparable to control plants down to –3°C. Plants exposed to –3°C had 50% to 80% fruit set when treated with GA3 compared to 5% to 19% fruit set for untreated plants. Temperatures of –4.5°C caused severe flower damage, and fruit set by pollination or GA3 was very poor (<2%). These results indicate that GA3 should be useful in salvaging a blueberry crop exposed to temperatures of – 1 to –3.5°C during bloom.

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