scholarly journals 334 Seasonal Characterization of the Phenolic Layer Beneath Floral Buds of Rhododendron spp.

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 500E-500
Author(s):  
Michelle R. Salemi ◽  
James D. Scott ◽  
Linda Chalker-Scott
Keyword(s):  
Thermal Analysis ◽  
Low Temperature ◽  
Fluorescence Microscopy ◽  
Preliminary Analysis ◽  
Cold Hardiness ◽  
Floral Buds ◽  
Dormant Season ◽  
Cold Hardy ◽  
The Relationship

It has been previously shown that dormant, cold-hardy floral buds of Azalea possess layers of highly lignified and suberized cells below the bud axis and beneath each bud scale. Two species of deciduous Azalea were analyzed bi-weekly using differental thermal analysis (DTA) throughout their dormant season to determine the development of cold hardiness as denoted by low temperature exotherms (LTEs). Other buds collected at the same time were observed using fluorescence microscopy to document the relationship between the development of the barrier and the onset of cold hardiness. Preliminary analysis showed when buds were maximally cold hardy the barrier was most intact, and as buds began to lose hardiness, the layer started to degrade. These results suggest that in fact this layer of cells does act as the long-proposed bud barrier. In a comparison between the species, the hardier species (R. japonicum) was found to have a denser layer of phenolic-rich cells compared to buds of the less hardy species (R. occidentale). This finding further supports the relationship between the layer of cells and the existence of cold hardiness in bud tissues.

A comparison of the cold hardiness of populations of Delia radicum (L.) (Diptera: Anthomyiidae) from southern England and the Canadian Prairies

1990 ◽  
Vol 68 (5) ◽  
pp. 830-835 ◽  
Author(s):  
W. J. Turnock ◽  
P. M. Reader ◽  
G. K. Bracken
Keyword(s):  
Low Temperature ◽  
Cold Hardiness ◽  
Cold Injury ◽  
Delia Radicum ◽  
Supercooling Point ◽  
Canadian Prairies ◽  
Canadian Population ◽  
English Population ◽  
Cold Hardy ◽  
The Relationship

The Canadian population of Delia radicum is more cold hardy than the English population in that the supercooling point is slightly lower and overwintering pupae are less sensitive to lower temperatures and longer exposure times. However, the Canadian population is slightly less cold hardy at higher temperatures within the cold injury zone. Female D. radicum were more susceptible to cold-induced mortality than males among the Canadian population, but this sex difference was not significant in the English population. The proportion of malformed adults and the rate of postdiapause development were not related to cold injury in either population. The bounds of the cold injury zone for species or populations of freezing susceptible, diapausing insects plus the sensitivity of the species to cold injury within this zone can provide an ecologically sound method of describing cold hardiness. Sensitivity, measured by the slope of a regression describing the relationship between survival and the duration of exposure at a low temperature, can also be used to calculate the rate at which cold injury occurs at any temperature within the cold injury zone. This slope may reflect the overwintering conditions of a species or population because Canadian populations of both D. radicum and Mamestra configurata (Noctuidae) have similar coefficients, but these are very different from the coefficient of the English population of D. radicum. The supercooling point did not provide a useful indication of the susceptibility of these cold-hardy diapausing insects to cold injury.

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

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 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 Cloning and Expression of Dehydrin Genes in Blueberry

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 585a-585 ◽  
Author(s):  
Lisa J. Rowland ◽  
Mubarack Muthalif ◽  
Amnon Levi ◽  
Rajeev Arora
Keyword(s):  
Low Temperature ◽  
Cdna Clone ◽  
Cloning And Expression ◽  
Sequence Information ◽  
Floral Buds ◽  
Growth Characterization ◽  
Dna Primers ◽  
Rna Blots ◽  
Dehydrin Genes

Previous studies identified three major chilling-responsive proteins of 65, 60, and 14 kDa whose levels increase in floral buds of blueberry during cold acclimation and decrease during deacclimation and resumption of growth. Characterization of these proteins found them to be members of a family of proteins responsive to drought and low temperature stress called dehydrins. The 65- and 60-kDa proteins were purified, digested into peptides, and several peptides from each were sequenced. The sequence information was used to synthesize degenerate DNA primers for amplification of a part of the gene(s) encoding these proteins. One pair of primers amplified a 200-bp fragment, which now has been cloned and sequenced. Within the 200-bp sequence is a motif conserved amongst dehydrins. Hybridization of the 200-bp fragment to RNA blots revealed homology to two chilling-responsive messages of 3.7 and 1.6 kb. The 200-bp fragment currently is being used to screen a cDNA library (prepared from RNA from cold acclimated blueberry floral buds) to isolate the full length cDNA clone.

The Microstructure Evolution and Twinning Characterization of AZ31 Mg Alloy Sheet in Low-Temperature Bending Process

2013 ◽  
Vol 690-693 ◽  
pp. 16-19
Author(s):  
Jun Wei Liu ◽  
Shi Qiang Lu ◽  
Ke Lu Wang ◽  
Gui Fa Li ◽  
Xuan Xiao
Keyword(s):  
Low Temperature ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Alloy Sheet ◽  
Mg Alloy ◽  
Az31 Mg Alloy ◽  
Bending Process ◽  
Hot Rolled ◽  
The Relationship

The relationship among stress, cavities and twinning in the room-temperature bending process of hot-rolled AZ31 Mg alloy sheet was researched. It can be seen that the mount of twins which was tightly affected by stress value increases with the distance to press point. Otherwise, the cavities and twinning which seem totally independent, in fact affect with each other. Some cavities were hindered by twins and can not further grow up. Then, the relationship between slip and twinning was also roughly discussed. The dislocation lines in twins can be thought to release the stress focus and were beneficial for deformation.

Low-Temperature Oxidation and Characterization of Heavy Oil via Thermal Analysis

2015 ◽  
Vol 29 (2) ◽  
pp. 1151-1159 ◽  
Author(s):  
Wan-Fen Pu ◽  
Cheng-Dong Yuan ◽  
Fa-Yang Jin ◽  
Lei Wang ◽  
Zhen Qian ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Low Temperature ◽  
Heavy Oil ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation

scholarly journals Low-temperature Exotherms and Freeze Tolerance in Three Taxa of Deciduous Trees

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 849A-849
Author(s):  
Orville M. Lindstrom ◽  
Tomasz Anisko ◽  
Michael A. Dirr
Keyword(s):  
Low Temperature ◽  
Cold Hardiness ◽  
Acer Rubrum ◽  
Freeze Tolerance ◽  
Reliable Estimate ◽  
Fraxinus Americana ◽  
Deep Supercooling ◽  
The Difference ◽  
The Relationship ◽  
Zelkova Serrata

Although differential thermal analysis has been routinely used to evaluate cold hardiness, the relationship between deep supercooling ability and plant survival is not clear. We compared seasonal profiles of changes in low-temperature exotherm (LTE) occurrence and visually determined lowest survival temperature (LST) of Acer rubrum `Armstrong', Fraxinus americana `Autumn Purple' and Zelkova serrata `Green Village' growing in three locations representing plant cold hardiness zones 8, 7 and 5. Between December and February, LTE in Acer rubrum and Fraxinus americana occurred at temperatures 10 to 25C lower than the LST. The difference between LTE and LST was not significant for Zelkova serrata from January to April, and for Acer rubrum and Fraxinus americana in March. Data indicate that LTE could be used as an estimate of LST in Zelkova serrata but not in Acer rubrum and Fraxinus americana. This study demonstrated that LTE does not provide a reliable estimate of cold hardiness in all species that deep supercool.

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