scholarly journals Low-temperature Exotherm Measurement Using Infrared Thermography

HortScience ◽  
1995 ◽  
Vol 30 (1) ◽  
pp. 140-142 ◽  
Author(s):  
Toni L. Ceccardi ◽  
Robert L. Heath ◽  
Irwin P. Ting
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Low Temperature ◽  
Infrared Thermography ◽  
Computer Analysis ◽  
Freezing Temperature ◽  
Simmondsia Chinensis ◽  
Analysis Software ◽  
Color Changes

Infrared thermography was used successfully to measure the exotherm temperatures during freezing of well-watered and drought-stressed branches of jojoba [Simmondsia chinensis (Link) Schneider]. The exotherms were visualized easily as color changes on the monitor, while computer analysis software was used to plot the resulting temperature vs. time curves, suggesting that freezing sensitivity of jojoba is governed by supercooling. Each branch froze as a unit, and distinct initiation sites were absent. A second, previously tested method of differential thermal analysis was used simultaneously and confirmed the accuracy of the infrared technique. The actual freezing temperature for well-watered tissue was higher (–8C) than for tissue subjected to drought (–10C).

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 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.

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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