PRELIMINARY OBSERVATIONS ON THE EFFECTS OF HYDROGEN CYANAMIDE ON BREAKING DORMANCY IN FLOWER BUDS OF JOJOBA (SIMMONDSIA CHINENSIS) IN PARAGUAY

1995 ◽  
pp. 165-170
Author(s):  
Julio G. Spinzi
Keyword(s):  
Simmondsia Chinensis ◽  
Flower Buds ◽  
Hydrogen Cyanamide ◽  
Breaking Dormancy

Jojoba flower buds: temperature and photoperiod effects in breaking dormancy

1980 ◽  
Vol 31 (4) ◽  
pp. 727 ◽  
Author(s):  
RL Dunstone
Keyword(s):  
Seed Weight ◽  
Diurnal Temperature Range ◽  
Night Temperature ◽  
Flower Buds ◽  
Flower Bud ◽  
Desert Shrub ◽  
Breaking Dormancy ◽  
Controlled Environments ◽  
Effects Of Temperature ◽  
Lower Temperature

Jojoba (Simmondsia chinensis [Link] Schneid.) is a long-lived desert shrub, valued for the liquid wax which makes up 50% of the seed weight. As attempts are being made to domesticate the species, it is important to understand the environmental factors controlling the reproductive cycle and governing seed yield. The effects of temperature and photoperiod in breaking flower bud dormancy were studied on plants growing under well-watered conditions in controlled environments. Plants 42-48 months old produced only dormant flower buds when growing in 27/22� to 36/31�C day/night temperature. When the plants were moved to lower temperatures of 24/19� or 18/13�, every plant produced a flowering flush. In two experiments, clonal material was grown at either 30/25� or 36/3l�C, then moved to lower temperature treatments. Down to the lowest temperature used (18/13�), the greater the drop in temperature, the greater the number of flowers which opened. Flowering occurred under both short (8 h) or long (16 h) photoperiods. There was a critical temperature in the region of 27/22� to 30/25�, above which no flowering occurred. Flowering was not dependent on a large diurnal temperature range, but occurred only if the plants were subjected to a low temperature for at least 21 days.

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.

The potential of jojoba (Simmondsia chinensis) in New South Wales. 2. Some factors affecting yield

1989 ◽  
Vol 29 (3) ◽  
pp. 389 ◽  
Author(s):  
PL Milthorpe ◽  
RL Dunstone
Keyword(s):  
New South ◽  
New South Wales ◽  
Frost Damage ◽  
High Rate ◽  
High Yield ◽  
Simmondsia Chinensis ◽  
Chilling Requirement ◽  
Flower Buds ◽  
Flower Opening ◽  
South Wales

A jojoba (Simmondsia chinensis [Link] Schneider) stand at Condobolin. N.S.W.. established from a range of plant material, exhibited great variability in a number of plant characteristics including seed yield. Observations over 4 years indicated that a high bud to node ratio is necessary for high yield. Different lines varied from 44 to 74% in this ratio in the fourth year of study. The survival of buds to form open flowers varied greatly between lines and from year to year. Death of flower buds before opening was attributable to frost damage. Buds swelled as early as June in some lines while others showed no sign of swelling until September. In those lines with early swelling or flower opening a high proportion of the buds were frost damaged, whereas late flowering lines had a high rate of survival. Terminal flower buds formed just prior to winter dormancy survived and flowered in the next spring, even in otherwise early flowering lines. Earlier work has shown that jojoba flower buds remain dormant until a chilling requirement has been met. Jojoba lines should have a long chilling requirement to maintain dormancy in the buds until the danger of frosts is past. Almost all of the flowers that opened set fruit, indicating that pollination is not a problem in the New South Wales environment.

scholarly journals Treatments to Accelerate Leaf Development in Blueberries

HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 595D-595 ◽  
Author(s):  
Gerard Krewer ◽  
D. Scott NeSmith ◽  
Ben Mullinix
Keyword(s):  
Flower Development ◽  
Leaf Development ◽  
Late Summer ◽  
Bud Break ◽  
Benzyl Adenine ◽  
Flower Buds ◽  
Hydrogen Cyanamide ◽  
Dormancy Period ◽  
Spring Leaf ◽  
Vegetative Bud

Poor blueberry leaf development is a serious problem in medium and low chilling regions which leads to smaller, later ripening fruit and reduced bush vigor. Dormex (hydrogen cyanamide) and Promalin or Accel (6-benzyl adenine plus gibberellins A4 and A7) were used in the experiments. Dormex 1991-1995 trials with applications at the end of the dormancy period (February) looked promising but were not uniformly successful. In 1996, applications were made starting in mid-dormancy (early-mid January) about 6-8 weeks before normal bud break. Spring vegetative bud development was greatly accelerated with minimal advance in flower development. Mid-dormancy Dormex rates of 1.5% to 2% appear promising. Dormex application after bud break or at excessively high rates will kill flower buds, but has excellent potential as a bloom thinning agent for juvenile blueberry plants. Promalin or Accel applications post bloom significantly accelerated spring leaf development. Late summer applications of Promalin significantly increased fall growth and number of side shoots.

scholarly journals Chilling Exposure and Hydrogen Cyanamide Interact in Breaking Dormancy of Grape Buds

HortScience ◽  
1995 ◽  
Vol 30 (6) ◽  
pp. 1244-1247 ◽  
Author(s):  
N.K. Dokoozlian ◽  
L.E. Williams ◽  
R.A. Neja
Keyword(s):  
Vitis Vinifera ◽  
Economic Benefits ◽  
Gradual Decline ◽  
Hydrogen Cyanamide ◽  
Late Fall ◽  
Breaking Dormancy

An experiment was conducted to examine the interaction between chilling exposure (0, 50, 100, 200, 400, and 800 hours at 3C) and hydrogen cyanamide (H2CN2) concentration [0%, 1.25%, and 2.50% (v/v)] on the budbreak of dormant grape buds (Vitis vinifera L. `Perlette') collected in late fall before the onset of temperatures ≤13C. Budbreak at 22C was most rapid for cuttings exposed to 800 chill hours and least rapid for cuttings that received no chilling. Budbreak of cuttings receiving 50 to 200 hours of chilling was similar and lagged behind that of cuttings exposed to 400 or 800 hours. Maximum observed budbreak improved with increased chilling exposure. Hydrogen cyanamide hastened the growth of all chilling treatments and increased the percent budbreak of cuttings receiving ≤400 chill hours. When cuttings were not treated with H2CN2, the number of days required for 50% budbreak declined sharply as chilling exposure increased from 0 to 400 hours. In contrast, this interval was reduced only slightly as chilling increased from 400 to 800 hours. Hydrogen cyanamide-treated buds exhibited a more gradual decline in the number of days required for 50% budbreak with increased chilling exposure. In this study, the physiological efficacy and economic benefits of H2CN2 applications diminished with increased chilling exposure.

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 Effect of 9-Hydroxy-10-oxo-12(Z), 15(Z)-octadecadienoic Acid (KODA) on Endodormancy Breaking in Flower Buds of Japanese Pear

HortScience ◽  
2010 ◽  
Vol 45 (10) ◽  
pp. 1470-1474 ◽  
Author(s):  
Daisuke Sakamoto ◽  
Yuri Nakamura ◽  
Hiroyoshi Sugiura ◽  
Toshihiko Sugiura ◽  
Toshikazu Asakura ◽  
...  
Keyword(s):  
Octadecadienoic Acid ◽  
Optimal Concentration ◽  
Japanese Pear ◽  
Pyrus Pyrifolia ◽  
Flower Buds ◽  
Effective Agent ◽  
Hydrogen Cyanamide

The effect of 9-hydroxy-10-oxo-12(Z), 15(Z)-octadecadienoic acid (KODA) on endodormancy breaking was studied in flower buds of japanese pear (Pyrus pyrifolia Nakai). The optimal concentration of KODA (100 μM) for endodormancy breaking was established over a 2-year period during the endodormancy stage of 2006 and 2007 in japanese pear cultivars Kosui, Natsushizuku, and Hosui. The effect of KODA on endodormancy breaking in flower buds was similar between ‘Natsushizuku’ and ‘Kosui’ but somewhat lower in ‘Hosui’. These results indicate that KODA can be an effective agent for promoting endodormancy breaking of flower buds in ‘Natsushizuku’ and ‘Kosui’. Although not as effective as hydrogen cyanamide, KODA may be preferable at late endodormancy stages because it has no apparent phytotoxicity.

scholarly journals “TIFBLUE' BLUEBERRY BUDBREAK BY H2CN2 AT DIFFERENT DORMANCY STAGES

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 689d-689
Author(s):  
M.R. Mohd. Saad ◽  
Russell L. Weiser
Keyword(s):  
Hot Water ◽  
Distilled Water ◽  
Flower Buds ◽  
Growth Season ◽  
Vaccinium Ashei ◽  
Hydrogen Cyanamide ◽  
Chilling Temperatures

`Tifblue' Blueberries (Vaccinium ashei) have poor or delayed budbreak in warm growing regions due to a lack of chilling temperatures. Hydrogen cyanamide(H2CN2) is known to break dormancy in buds. We tested the response of `Tifblue' blueberry buds to concentrations of hydrogen cyanamide at different dormancy stages with respect to budbreak and phytotoxicity. Blueberry bud sticks were harvested during the growth season at three week intervals. H2CN2 (0.05, 0.125, 0.25, 0.5 M), hot water (47C) and a control (distilled water at 0C) were used. Treated bud sticks were forced to break under light at 18-26C. Flower and leaf buds broke after 10-14 days. H2CN2 above 0.25 M was highly phytotoxic to flower buds, but not leaf buds. H2CN2 at 0.125 M was most effective in breaking flower and leaf buds at all dormancy stages. ABA and polyamine levels in buds shall be analyzed.

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