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%).

Effects of hydrogen cyanamide, paclobutrazol and pruning date on dormancy release of the low chill peach cultivar Flordaprince in subtropical Australia

1992 ◽  
Vol 32 (1) ◽  
pp. 89 ◽  
Author(s):  
AP George ◽  
J Lloyd ◽  
RJ Nissen
Keyword(s):  
Growth Regulator ◽  
Growth Retardant ◽  
The Other ◽  
Dormancy Release ◽  
Early Winter ◽  
Harvest Time ◽  
Hydrogen Cyanamide ◽  
Peach Cultivar ◽  
Fruit Maturity ◽  
Subtropical Australia

The growth regulator hydrogen cyanamide (Dormex, 50% a.i.) was tested for its effectiveness in promoting earlier and more even budbreak, flowering, and fruit maturity of the low chill peach cv. Flordaprince at 2 sites in subtropical Australia. The influence of the growth retardant paclobutrazol was also tested at 1 site, and at the other, the effect of altering pruning date. At 1 site only, hydrogen cyanamide applied early-mid June, during endodormancy, advanced mean harvest time by 10 days. At the other site, there were no consistent trends between harvest time and date of application of cyanamide. Dormex at the lowest concentration applied (10 mL/L) caused severe yield reductions (40.8%). Flowering and fruit maturity were advanced by about 6 days with dormant pruning in early winter, compared with pruning at later dates, and by 13 days with the application of the growth retardant paclobutrazol, compared with no application.

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.

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).

Effects of postharvest topping, autumn cincturing, and paclobutrazol on growth, yield, and fruit quality of the low chill nectarine cv. Sundowner in subtropical Australia

1993 ◽  
Vol 33 (3) ◽  
pp. 353 ◽  
Author(s):  
AP George ◽  
RJ Nissen ◽  
T Rassmussen
Keyword(s):  
Fruit Quality ◽  
Seasonal Pattern ◽  
Growth Yield ◽  
Tree Size ◽  
Yield Efficiency ◽  
Fruit Maturity ◽  
Canopy Volume ◽  
Effect On Yield ◽  
Subtropical Australia

Combinations of 3 methods of controlling tree size (use of the growth retardant paclobutrazol, postharvest topping, and autumn cincturing) were evaluated for their effects on growth, yield, and fruit quality of the low chill nectarine cv. Sundowner in subtropical Australia. Compared with controls over 3 seasons, paclobutrazol used alone reduced tree size by 34-52%, with further reductions when combined with light and severe postharvest topping (by 5-25 and 58-71%, respectively). Yield efficiency (as measured by yield per unit canopy volume) was significantly improved by paclobutrazol and was doubled when paclobutrazol was combined with severe postharvest topping. Although this combination reduced time associated with pruning, thinning, and harvesting, it had the disadvantage of delaying flowering and, consequently, fruit maturity in the subsequent harvest season. Light postharvest topping and autumn cincturing used with paclobutrazol had little effect on yield efficiency, fruit quality, or harvest period. The seasonal pattern of starch reserves for twigs was similar for all treatments, with starch levels falling to a minimum during the early harvest period. Measurements of starch in the major tree organs showed that at very low harvest increments (<10) there was little or no depletion of starch from the twigs and leaves, but as harvest increments increased (range 10-40), there was increasing starch depletion, in order of priority, from the roots, trunks, and limbs.

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

scholarly journals EFFECTS OF HYDROGEN CYANAMIDE ON APPLE AND PLUM FRUIT THINNING

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 690a-690
Author(s):  
Esmaeil Fallahi ◽  
Brenda R. Simons ◽  
John K. Fellman ◽  
W. Michael Colt
Keyword(s):  
Malus Domestica ◽  
Fruit Set ◽  
Fruit Size ◽  
Apple Fruit ◽  
Fruit Weight ◽  
Full Bloom ◽  
Hydrogen Cyanamide ◽  
Fruit Thinning ◽  
Prunus Salicina

Influence of various concentrations of hydrogen cyanamide (HC) on fruit thinning of `Rome Beauty' apple (Malus domestica Borkh.), `Friar,' and `Simka' plums (Prunus salicina Lindley) were studied. A full bloom application of HC at all tested concentrations decreased `Rome Beauty' apple fruit set and yield, and increased fruit weight. Hydrogen cyanamide at 0.25% (V/V) resulted in adequate apple thinning, indicated by the production of an ideal fruit weight. Prebloom and full bloom applications of HC at greater than 0.75% reduced plum fruit set and yield in `Friar.' Full bloom application of HC at 0.25% to 0.50% showed a satisfactory fruit set, yield, and fruit size in `Friar' plum. Full bloom application decreased fruit set and yield in `Simka' plum. Hand thinning, as well as chemical thinning, is recommended for plums.

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