Chemical methods on breaking dormancy of low chill nectarines: preliminary evaluations in subtropical Queensland

1988 ◽  
Vol 28 (3) ◽  
pp. 425 ◽  
Author(s):  
AP George ◽  
RJ Nissen
Keyword(s):  
Fruit Set ◽  
Potassium Nitrate ◽  
Yield Losses ◽  
Chemical Methods ◽  
Hydrogen Cyanamide ◽  
Breaking Dormancy ◽  
Fruit Maturity ◽  
Final Yield

Three chemicals, Alzodef (49% hydrogen cyanamide) at 20 mL/L, thiourea at 10 g/L and potassium nitrate at 40 g/L were tested either alone or in combination for their effects on breaking dormancy in the low chill nectarine cultivar Sunred in subtropical Queensland. Compared with potassium nitrate and thiourea, Alzodef proved more effective in breaking dormancy and advancing budbreak and fruit maturity. However, Alzodef reduced both fruit set and final yield. Yield losses were greater when application of Alzodef was delayed from 5 weeks to 1 week before natural budbreak.

Effects of growth regulants on defoliation, flowering, and fruit maturity of the low chill peach cultivar Flordaprince in subtropical Australia

1993 ◽  
Vol 33 (6) ◽  
pp. 787 ◽  
Author(s):  
AP George ◽  
RJ Nissen
Keyword(s):  
Fruit Set ◽  
Potassium Nitrate ◽  
Hydrogen Cyanamide ◽  
Peach Cultivar ◽  
Fruit Maturity ◽  
Subtropical Australia

The growth regulants paclobutrazol, hydrogen cyanamide (Dormex 500 g a.i./L), and potassium nitrate were tested for their effectiveness in promoting earlier and more even budbreak, flowering, and fruit maturity of the low chill peach cultivar Flordaprince in subtropical Australia. Paclobutrazol advanced harvest by about 10 days. Hydrogen cyanamide was effective in advancing fruit maturity by about 19 days, but even at the lowest concentration used (5 mL/L), it severely reduced fruit set by >4 0 % . In contrast, 1-3 sequentially autumn-applied potassium nitrate sprays advanced flowering by about 10 days; >3 applications caused significant (P<0.05) yield reductions (29%).

scholarly journals Regulating Budbreak, Flowering, and Fruit Maturity in Sweet Cherry (Prunus avium L.) cv. `Bing' by Surfactant and Nitrate Applications

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 603e-603
Author(s):  
K.G. Weis ◽  
S.M. Southwick ◽  
J.T. Yeager ◽  
W.W. Coates ◽  
Michael E. Rupert
Keyword(s):  
Sweet Cherry ◽  
Prunus Avium ◽  
Fruit Set ◽  
Fruit Size ◽  
Calcium Nitrate ◽  
Potassium Nitrate ◽  
Fruit Weight ◽  
Full Bloom ◽  
Fruit Maturity ◽  
Flower And Fruit Development

The years 1995 and 1996 were low chill years in California with respect to stone fruit dormancy. Advancing reproductive budbreak and flowering was accomplished in `Bing' cherry (Prunus avium) by single-spray treatments of a surfactant {a polymeric alkoxylated fatty amine [N,N-bis 2-(omega-hydroxypolyoxyethylene/polyoxypropylene) ethyl alkylamine]} and potassium nitrate in combination when applied at “tightbud,” ≈ 42 days (1 Feb. 1995) before full bloom and with surfactant and potassium nitrate in combination when 10% green calyx was apparent, 33 days before full bloom. Applying 2% surfactant (v/v) + 6% potassium nitrate (w/v) was most effective in advancing bloom, speeding progression through bloom, and advancing fruit maturity when applied at tightbud stage. Surfactant (2% or 4%) applied with 25% or 35% calcium nitrate (w/v) on 2 Feb. 1996 significantly advanced full bloom compared to nontreated controls. Fruit maturity (1995) was somewhat advanced by surfactant–nitrate treatments, but fruit set and final fruit weight were equivalent among treatments. No phytotoxicity was noted in foliage or fruit. In California, marginal and insufficient winter chilling often causes irregular, extended, or delayed bloom periods, resulting in poor bloom-overlap with pollenizers. As a result, flower and fruit development may be so variable as to have small, green and ripe fruit on the same tree, making harvest more time consuming and costly. Data indicate that this surfactant, in combination with a nitrogenous compound, has potential to advance reproductive budbreak and advance maturity in sweet cherry without reducing fruit set or fruit size. Advancing the ripening time of sweet cherry even 2 to 3 days can increase the price received per 8.2-kg box by $10 to $20.

scholarly journals 467 Overcoming Dormancy, Advancing Budbreak, and Advancing Fruit Maturity in `Bing' Sweet Cherry (Prunus avium L.): Surfactants/ Dormant Oils + Calcium Ammonium Nitrate or Hydrogen Cyanamide

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 525B-525 ◽  
Author(s):  
K.G. Weis ◽  
S.M. Southwick ◽  
J.T. Yeager ◽  
M.E. Rupert ◽  
R.E. Moran ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Untreated Control ◽  
Sweet Cherry ◽  
Prunus Avium ◽  
Fruit Set ◽  
Central Valley ◽  
Fruit Weight ◽  
Calcium Ammonium Nitrate ◽  
Hydrogen Cyanamide ◽  
Fruit Maturity

In continuing trials (1995-current), we have used a variety of treatments to overcome inadequate chilling, coordinate bloom, improve leaf out and cropping, and advance/coordinate maturity in sweet cherry, cv. Bing. Treatments have included hydrogen cyanamide (HCN, Dormex) and various surfactants or dormant oils combined with calcium ammonium nitrate (CAN17). Chill hour accumulation, (required chilling for `Bing' = 850 to 880 chill hours) has varied greatly in each dormant season from 392 (Hollister, 1995-1996) to adequate, depending both on the season and location (central valley vs. coastal valley). In 1998, 4% HCN advanced budbreak significantly compared to any other treatment, although other chemical treatments also were more advanced than the untreated control. Dormex advanced completion of bloom 11% to 40% more than other treatments, although other dormancy-replacing chemicals were at least 16% more advanced in petal fall than the untreated control. Dormex contributed to slightly elevated truss bud death, as did 2% Armobreak + 25% CAN17. In 1998, fruit set was improved by 2% Armobreak + 25% CAN17 (79%) compared to the untreated control (50%); all other treatments statistically equaled the control. Fruit set was not improved by Dormex, although bloom was advanced by a few days in this treatment. As fruit set was increased by treatments, rowsize decreased (as did fruit weight), as expected, but no treatment resulted in unacceptable size. In 1997, fruit set was also improved by 2% Armobreak + 25% CAN17; however, fruit set was so low overall in that year that no real impact was found. In 1997 and 1998, 4% HCN advanced fruit maturity compared to other treatments, with darker, softer, larger fruit at commercial harvest. These and additional results will be presented.

Control of Dormancy and Budbreak in Sweet Cherry (Prunus avium L.) cv `Bing' with Surfactant + Calcium Ammonium Nitrate and Hydrogen Cyanamide

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 514c-514
Author(s):  
K.G. Weis ◽  
S.M. Southwick ◽  
J.T. Yeager ◽  
M.E. Rupert ◽  
W.W. Coates
Keyword(s):  
Ammonium Nitrate ◽  
Prunus Avium ◽  
Fruit Set ◽  
Full Bloom ◽  
Calcium Ammonium Nitrate ◽  
Hydrogen Cyanamide ◽  
Minimum Requirement ◽  
Nitrate Treatment ◽  
Fruit Maturity ◽  
San Joaquin County

Continuing trials (1995–present) advanced budbreak and flowering with a surfactant and calcium ammonium nitrate (CAN17), and in 1997, hydrogen cyanamide (HCN). Chilling in 1996–1997 was marginal in San Joaquin County (SJ, 830 chill hours, 18 Feb.), and low in San Benito County (SB, 612 chill hours, 21 Feb.). When we used the “45 °F” chilling model, the most effective surfactant + nitrate treatment timings for both locations were similar by chill accumulation (≈72 % to 82% of required chilling for `Bing' = 850–880 chill hours), although the two locations differed in total chill accumulation and date of effective treatment. Full bloom (FB) was advanced by 1 week with 4% HCN in SJ, followed by 2% surfactant + 25% calcium ammonium nitrate applied on 21 Jan. (700 chill hours), compared to the untreated control. Bloom duration (full bloom to petal fall) was compressed most by surfactant and CAN17. Bloom in SB was also most advanced by HCN, followed by 2% surfactant + 25% CAN17 applied on 21 Feb. (612 chill hours). Fruit set was improved in SB by surfactant and CAN17 in mid-February; set was too low, however, for real impact. In SJ and SB, HCN advanced fruit maturity most, followed by surfactant and CAN17 applied 21 Jan.; these fruits were softer. We believe that, in order for treatments to be effective in advancing budbreak and full bloom, some minimum amount of chilling must be accumulated prior to application (perhaps 60% to 75% of chilling requirement). We have also determined that where chilling is well below minimum requirement, higher rates of CAN (25%) are necessary to advance bloom. A further advantage of using Armobreak + CAN is improved N level in buds and bark after treatment (1997).

scholarly journals Changes in Promoter and Inhibitor Substances During Dormancy Release in Apple Buds Under Foliar-Applied Dormancy-Breaking Agents

2018 ◽  
pp. 1-20 ◽  
Author(s):  
Mohamed A. Seif El-Yazal
Keyword(s):  
Fruit Set ◽  
Phenolic Content ◽  
Bud Break ◽  
Dormancy Breaking ◽  
Hydrogen Cyanamide ◽  
Flowering Duration ◽  
Winter Conditions ◽  
Malus Sylvestris ◽  
Final Yield ◽  
Indole 3 Acetic Acid

The effect of hydrogen cyanamide (Dormex) at different concentrations for reaching early break dormancy in buds of "Astrachan" apple (Malus sylvestris, Mill) trees and their effects on metabolic changes in the content of buds from promoter and inhibitor substances during their release from dormancy was investigated. The efficiency of early bud break was noticed in varying degrees with Dormex at different concentrations. All applied concentrations led to early bud break, short flowering duration, high percentages of bud break and fruit-set, high contents of total indoles, indole-3-acetic acid, gibberellic acid, total and conjugated phenols and low content of abscisic acid and free phenols. These results were positively reflected in the final yield. Accordingly, we recommend using Dormex at 3% for reaching the early break dormancy in buds of "Astrachan" apple trees under Egyptian winter conditions and maximizing the yield by regulating the hormonal and phenolic content in buds.

Comparison of pre-treatments for inducing germination in highly dormant wheat genotypes

2003 ◽  
Vol 83 (4) ◽  
pp. 729-735 ◽  
Author(s):  
M. A. Matus-Cádiz ◽  
P. Hucl
Keyword(s):  
Seedling Growth ◽  
Biomass Yield ◽  
Triticum Aestivum L ◽  
Potassium Nitrate ◽  
Dormancy Breaking ◽  
Yield Data ◽  
Breeding Populations ◽  
Breaking Dormancy ◽  
Seedling Length ◽  
Pre Treatment

An effective dormancy-breaking method may be of interest to wheat (Triticum aestivum L.) breeders selecting for increased seed dormancy prior to advancing their populations in greenhouse grow-outs. The objective of this study was to identify an effective pre-treatment for breaking dormancy in wheat that did not result in seedling etiolation. In 2000, eight dormant (W98616, line 211, EMDR-4, EMDR-9, EMDR-14, RL4137, Columbus, and AC Domain) and one nondormant line (Roblin) were grown at two locations in Saskatchewan. Seeds were: (i) stored for zero to 21 wks at 24°C before incubating at 20°C for 7 d; (ii) incubated at 5, 10, 15, 20, and 25°C for 14 d; and (iii) treated with gibberellic acid (GA3) (0.0006 and 0.0014 M), potassium nitrate (KNO3) (0.01 and 0.02 M), chilling, heating, chilling with 0.01 M KNO3, and heating with 0.01 M KNO3 before incubating at 10°C for 14 d. Seedling growth was observed in a duplicated growth chamber experiment. Seedling length, first inter-node length, and biomass yield data were collected from plants grown from seeds treated with four effective pretreatments. Data were subjected to an ANOVA. Six to 18 weeks of storage at 24°C were required to break the dormancy (≥ 95% germination) in dormant genotypes. Incubation at 10°C was the most effective temperature for promoting germination in dormant seeds after 10d of testing. Four pre-treatments including 0.0006 M GA3, 0.0014 M GA3, chilling with 0.01 M KNO3, and heating with 0.01 M KNO3 led to ≥ 95% germination within 10 d of testing. Only GA3 treatments were associated with etiolated seedling growth. Heating with 0.01 M KNO3 or chilling with 0.01 M KNO3, applied before incubating at 10°C in darkness, may be of interest to breeders selecting for increased dormancy before advancing breeding populations in greenhouse grow-outs. Key words: Triticum, dormancy, nitrate, chilling, heating, etiolated seedling

EFFECT OF POTASSIUM NITRATE AND HYDROGEN CYANAMIDE ON APRICOT

1995 ◽  
pp. 431-440 ◽  
Author(s):  
U. Aksoy ◽  
S. Kara ◽  
A. Misirli ◽  
H.Z. Can ◽  
G. Seferoglu
Keyword(s):  
Potassium Nitrate ◽  
Hydrogen Cyanamide

Time of pruning affects fruit abscission, stem carbohydrates and yield of macadamia

2012 ◽  
Vol 39 (6) ◽  
pp. 481 ◽  
Author(s):  
Lisa McFadyen ◽  
David Robertson ◽  
Margaret Sedgley ◽  
Paul Kristiansen ◽  
Trevor Olesen
Keyword(s):  
Fruit Set ◽  
Photosynthetic Capacity ◽  
Water Soluble ◽  
Soluble Carbohydrates ◽  
Carbon Limitation ◽  
Yield Losses ◽  
Fruit Abscission ◽  
Macadamia Integrifolia ◽  
Water Soluble Carbohydrates ◽  
Stem Water

Macadamia (Macadamia integrifolia Maiden and Betche, M. tetraphylla Johnson and hybrids) orchards in Australia are typically hedged around anthesis (September). Such hedging reduces yields, largely through competition for carbohydrates between early fruit set and the post-pruning vegetative flush, but also through a reduction in photosynthetic capacity caused by the loss of canopy. We examined whether hedging at other times might mitigate yield losses. Hedging time was found to affect yields across four cultivars: ‘A4’, ‘A38’, ‘344’ and ‘816’. Yield losses were lower for trees hedged in November–December than for trees hedged in September. Yields for trees hedged in June were higher than for trees hedged in September in one experiment, but were similar in a second experiment. Yield losses for September and October hedging were similar. Hedging time changed the pattern of fluctuations in stem water-soluble carbohydrates (WSC). WSC declined shortly after hedging in September, October or November, and the declines preceded increases in fruit abscission relative to unpruned control trees. The increase in fruit abscission was less pronounced for the trees hedged in November, consistent with the idea that fruit become less sensitive to carbon limitation as they mature.

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