scholarly journals Supercooling and Extracellular Ice Formation in Differentiating -Buds of Eastern Thornless Blackberry

1992 ◽  
Vol 117 (6) ◽  
pp. 941-945 ◽  
Author(s):  
Michele R. Warmund ◽  
Fumiomi Takeda ◽  
Glen A. Davis
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Low Temperature ◽  
Floral Development ◽  
Early Spring ◽  
Ice Formation ◽  
Anatomical Studies ◽  
Terminal Flower ◽  
Floral Primordia ◽  
Thornless Blackberry

`Hull Thornless' and `Black Satin' blackberry (Rubus spp.) canes were collected from Sept. 1989 through Mar. 1990 to determine the hardiness and supercooling characteristics of buds at various stages of development. Anatomical studies were also conducted to examine the location of ice voids in buds frozen to -5 or -30C. Differentiation of the terminal flower occurred in `Black Satin' buds by 6 Nov., whereas `Hull Thornless' buds remained vegetative until early spring. As many as nine floral primordia were observed in both cultivars by 12 Mar. The hardiness of the two cultivars was similar until February. Thereafter, `Black Satin' buds were more susceptible to cold injury than those of `Hull Thornless'. Flora1 and undifferentiated buds of both cultivars exhibited one to four low temperature exotherms (LTEs) from 9 Oct. to 12 Mar. in differential thermal analysis (DTA) experiments. The stage of flora1 development did not influence the bud's capacity to supercool. The number of LTEs was not related to the stage of floral development or to the number of floral primordia. Extracellular voids resulting from ice formation in the bud axis and scales were observed in samples subjected to -5 or -30C.

scholarly journals CHARACTERIZATION OF ICE FORMATION IN BLUEBERRY FLOWER BUDS

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1088a-1088
Author(s):  
Cindy L. Flinn ◽  
Edward N. Ashworth
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Low Temperature ◽  
Ice Crystals ◽  
Ice Formation ◽  
Flower Buds ◽  
Woody Tissue ◽  
Cooling Rates

Examination of both frozen specimens and -5C freeze-fixed buds showed that ice crystals were not uniformly distributed in blueberry flower buds. Localized freezing was also evidenced by detection of multiple freezing events using differential thermal analysis (DTA). Upon cooling, an initial exotherm occurred just below 0C and coincided with ice formation in adjacent woody tissue. Multiple low temperature exotherms (LTE), which have been reported to correspond with the freezing of individual blueberry florets (Bierman, et al. 1979. ASHS, 104(4):444-449), occurred between -7C and -28C. The presence and temperature of LTEs was influenced by cooling rates and whether buds were excised. LTE temperatures did not correlate with hardiness of buds frozen under field-like conditions. Results suggested that DTA of excised buds was not an appropriate method for determining hardiness.

FREEZING SURVIVAL AND SUPERCOOLING IN PRIMARY AND SECONDARY BUDS OF Rubus spp.

1990 ◽  
Vol 70 (3) ◽  
pp. 893-904 ◽  
Author(s):  
M. R. WARMUND ◽  
M. F. GEORGE
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Low Temperature ◽  
Cold Hardiness ◽  
Rubus Idaeus ◽  
Freezing Injury ◽  
Red Raspberry ◽  
Viability Testing ◽  
Floral Buds ◽  
Floral Primordia

Primary and secondary buds from 11 blackberry (Rubus subgen. Rubus) and 10 red raspberry (Rubus idaeus) cultivars were subjected to viability testing to determine their relative hardiness from November 1987 through March 1988. Of the blackberries tested, Darrow floral buds were found to be the most hardy throughout dormancy. Forty-five percent of primordia in Darrow primary buds survived −33 °C in January. Most blackberries had reproductive secondary buds that generally survived lower temperatures than the primary buds. Of the red raspberries tested, Canby and Chilliwack had good primary bud hardiness in January and March. Primary buds of red raspberries were usually injured at warmer temperatures than secondary buds. Differential thermal analysis experiments were conducted on primary and secondary buds of Dirksen and Shawnee blackberry and Nordic and Reveille red raspberry at each test date to determine their freezing characteristics. The low temperature exotherms detected in primary buds of each cultivar were correlated with freezing injury, but their number seldom corresponded to the number of differentiated floral primordia. Low temperature exotherms were also detected in some of secondary buds of Dirksen and Reveille which contained differentiated floral primordia.Key words: Blackberries, raspberries, cold hardiness, differential thermal

Evaluation of low-temperature properties of gas oils via differential thermal analysis

1986 ◽  
Vol 31 (1) ◽  
pp. 21-31
Author(s):  
H. H. Abou El Naga ◽  
A. E. Salem ◽  
D. A. Abd El Ghaffar
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Low Temperature

scholarly journals 329 DIFFERENTIAL THERMAL ANALYSIS OF RABBITEYE BLUEBERRIES

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 477f-477
Author(s):  
Gena R. Hughes ◽  
Frank B. Matta
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Low Temperature ◽  
Cold Hardiness ◽  
Vaccinium Ashei ◽  
Tissue Browning

Acclimation and cold hardiness of blueberry buds (Vaccinium ashei cv. Tifblue) were evaluated using differential thermal analysis (DTA) and tissue browning. Buds exhibited a single exotherm at -7C October through December and at -11C January through April. LOW temperature exotherms (LTE) were not detected. Tissue browning test ratings indicated that ovary death occurred at -21C.

scholarly journals Dead Prunus Flower-bud Primordia Retain Deep-supercooling Properties

HortScience ◽  
1993 ◽  
Vol 28 (8) ◽  
pp. 831-832
Author(s):  
Sorkel A. Kadir ◽  
Ed L. Proebsting
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Low Temperature ◽  
Low Temperatures ◽  
Sweet Cherry ◽  
Prunus Dulcis ◽  
Flower Buds ◽  
Flower Bud ◽  
Flower Primordia ◽  
Deep Supercooling

Differential thermal analysis (DTA) was used to measure deep supercooling in flower buds of Prunus dulcis Mill., P. armeniaca L., P. davidiana (Carr.) Franch, P. persica (L.) Batsch, three sweet cherry (P. avium L.) selections, and `Bing' cherries (P. avium L.) during Winter 1990-91 and 1991-92. Low temperatures in Dec. 1990 killed many flower buds. After the freeze, dead flower primordia continued to produce low-temperature exotherms (LTEs) at temperatures near those of living primordia for >2 weeks. In Feb. 1992, cherry buds that had been killed by cooling to -33C again produced LTEs when refrozen the next day. As buds swelled, the median LTE (LTE50) of dead buds increased relative to that of living buds, and the number of dead buds that produced LTEs decreased. LTE artifacts from dead flower priimordia must be recognized when DTA is used to estimate LTE50 of field-collected samples.

scholarly journals Blueberry Flower-bud Hardiness Is Not Estimated by Differential Thermal Analysis

1994 ◽  
Vol 119 (2) ◽  
pp. 295-298 ◽  
Author(s):  
Cindy L. Flinn ◽  
Edward N. Ashworth
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Low Temperature ◽  
Vaccinium Corymbosum ◽  
Freezing Behavior ◽  
Flower Buds ◽  
Flower Bud ◽  
Cooling Rates ◽  
Stem Segments

Differential thermal analysis (DTA) was used to study the freezing behavior of `Berkeley' blueberry (Vaccinium corymbosum L.) flower buds at cooling rates of 10, 5, and 2C/hour. Experiments were conducted at various stages of hardiness on excised and attached (5 cm of stem) buds. The presence and number of low-temperature exotherms (LTEs) in hardy buds generally increased when analyses were conducted using faster cooling rates with excised buds. The number of LTEs detected in individual buds did not correlate (r2 = 0.27) with the number of injured florets. The inability to detect LTEs in buds attached to stem segments and cooled at 2C/hour indicates that DTA cannot reliably estimate blueberry flower-bud hardiness in field plantings.

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