RELATIONSHIP OF THE LOW TEMPERATURE EXOTHERM TO APPLE AND PEAR PRODUCTION IN NORTH AMERICA

1976 ◽  
Vol 56 (3) ◽  
pp. 493-500 ◽  
Author(s):  
H. A. QUAMME
Keyword(s):  
North America ◽  
Low Temperature ◽  
Cold Hardiness ◽  
Supercooled Water ◽  
Spontaneous Nucleation ◽  
Pyrus Communis L ◽  
Commercial Cultivars ◽  
Malus Pumila Mill ◽  
Apple Production ◽  
Relationship Of

Twig pieces from the current season’s growth of three crabapple (Malus sp.), eight apple (Malus pumila Mill.) and seven year (Pyrus communis L.)cultivars, and limb pieces from 6- to 7-yr-old branches of Starking Red Delicious apple and Bartlett pear were taken during mid-winter and-subjected to a preconditioning treatment to induce maximal cold hardiness. The apple and pear cultivars studied included many of the major commercial cultivars grown in North America. Freezing tests and differential thermal analysis (DTA) were performed on the twig and limb pieces after preconditioning. Xylem was the most susceptible in stem tissue of both preconditioned apple and preconditioned pear. The temperature at which apple and pear xylem of commercial cultivars became injured (−35 to −40 C and −30 to −35 C, respectively) was related to the initiation of the low temperature exotherm on the DTA profile (−37 to −40 C and −33 to −38 C, respectively) and in turn was related to the average annual minimum temperatures at the northern limits of commercial production (−34.4 to −40 C and −28.9 to −34.4 C, respectively). The low temperature exotherm was previously shown to be produced by freezing of supercooled water in the xylem. The spontaneous nucleation temperature of supercooled water in xylem of the cultivars studied appears to be related to the northern limit of pear and apple production in North America.

scholarly journals 367 Ripening Control of Pyrus communis L. Fruit with 1-MCP

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 507A-507
Author(s):  
R.S. Mueller ◽  
D.P. Murr ◽  
L.J. Skog
Keyword(s):  
Low Temperature ◽  
Commercial Application ◽  
Fruit Softening ◽  
Ethylene Receptor ◽  
Irreversible Binding ◽  
Ethylene Evolution ◽  
Cyclic Hydrocarbon ◽  
Commercial Use ◽  
Pyrus Communis L ◽  
Commercial Cultivars

1-Methylcyclopropene (1-MCP), a gaseous synthetic cyclic hydrocarbon, has been shown to have potential to become an important new tool in controlling the response of plants sensitive to ethylene. Due to its irreversible binding to the ethylene receptor(s) and its subsequent prevention of the physiological action of ethylene for extended periods, 1-MCP may prove also to have effective commercial application in the control of ethylene effects in detached organs such as fruit. Our objective was to investigate the effectiveness of 1-MCP in controlling ripening in pear. Two commercial cultivars (Bosc, Anjou) and one numbered cultivar from Agriculture and Agri-Food Canada's breeding program (Harrow 607) were harvested at commercial maturity. Immediately after harvest, fruit were exposed for 24 h at 20 °C to 1-MCP ranging from 0 to 100 μL•L-1 then placed in air at 0 °C and 90% relative humidity for 5 and 10 weeks. Following treatment and after 5 weeks storage plus a 7- or 14-day post-storage ripening period, fruit softening and ethylene evolution were inhibited and fruit volatile evolution was reduced significantly by exposure to 1-MCP at or above 1.0 μL•L-1 in all three cultivars. Concentrations exceeding 1.0 μL•L-1 were required to maintain initial firmness and inhibit ethylene production after 10 weeks storage in air. Evolution of alpha-farnesene and 6-methyl-5-hepten-2-one was related to low temperature stress and chlorophyll loss as a result of ripening, respectively, and were affected by 1-MCP exposure. The pattern of evolution and amounts of other volatiles was also affected by 1-MCP treatment. These results indicate a huge potential for commercial use and application of 1-MCP in controlling fruit ripening and senescence.

scholarly journals Low-temperature Exotherms and Cold Hardiness in Three Taxa of Deciduous Trees

1995 ◽  
Vol 120 (5) ◽  
pp. 830-834 ◽  
Author(s):  
Orville M. Lindstrom ◽  
Tomasz Anisko ◽  
Michael A. Dirr
Keyword(s):  
Low Temperature ◽  
Cold Hardiness ◽  
Acer Rubrum ◽  
Fraxinus Americana ◽  
Freeze Avoidance ◽  
Deep Supercooling ◽  
The Mean ◽  
Relationship Of ◽  
The Relationship ◽  
Zelkova Serrata

Although differential thermal analysis has been routinely used to evaluate cold hardiness, the relationship of deep supercooling ability and plant survival are not well understood. In this study, we compared the seasonal profiles of changes in low-temperature exotherm (LTE) occurrence with visually determined cold hardiness of Acer rubrum L. `Armstrong', Fraxinus americana L. `Autumn Purple' and Zelkova serrata (Thunh.) Mak. `Village Green' growing in three locations representing plant cold hardiness zones 8b, 7b, and 5a. Between December and February, LTEs in Acer rubrum `Armstrong' and Fraxinus americana `Autumn Purple' occurred at temperatures around 10 to 25C lower than the lowest survival temperatures. The mean difference between LTEs and lowest survival temperature was not significant for Zelkova serrata `Village Green' from January to April and for Acer rubrum `Armstrong' and Fraxinus americana `Autumn Purple' in March. Data indicated that LTEs could be used as an estimate of lowest survival temperature in Zelkova serrata `Green Village' but not in Acer rubrum `Armstrong' and Fraxinus americana `Autumn Purple'. This study demonstrated that LTEs may not reliably estimate cold hardiness in all species that deep supercool. Factors other than freeze avoidance ability of xylem may limit stem survival at temperatures above the LTE.

scholarly journals Hardiness and Ornamental Characteristics of Lacebark Elm Selections

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 448D-448
Author(s):  
John C. Pair ◽  
Channa Rajashekar ◽  
Michael Shelton
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Cold Hardiness ◽  
Room Temperature ◽  
Growth Form ◽  
Visible Injury ◽  
Ulmus Parvifolia ◽  
Commercial Cultivars

Numerous cultivars of lacebark elm (Ulmus parvifolia) have been introduced recently without adequate testing of their hardiness. A block of commercial cultivars plus numerous experimental numbers were established to observe differences in growth form, ornamental characteristics, and cold hardiness. Laboratory freezing tests were conducted from November to March over a 3-year period to determine acclimation and deacclimation to low temperatures. Stem sections approximately 5 cm long were sealed in test tubes and placed in a low-temperature programmable freezer maintained at 0°C. Samples were cooled by approximately 6°C per hour from 0 to –48°C and held for 1 h at each temperature. Samples were then removed, allowed to thaw at room temperature, and held for 7 to 10 days. Stem samples were sectioned longitudinally to observe browning in xylem and bark tissues. During the winter of 1995–96, no visible injury could be noted on trees in the field in spite of very dry, desiccating weather with temperatures reaching –23°C. Laboratory freezing tests indicated acclimation to –30°C by 18 Dec. 1995 on several cultivars. During warm periods in February, deacclimation occurred on many selections to –18°C, whereas others maintained a killing point of –30°C. Growth form, bark exfoliation, and fall color varied among cultivars.

scholarly journals Declining Foraging Efficiency in the Middle Tennessee River Valley Prior to Initial Domestication

2019 ◽  
Vol 84 (2) ◽  
pp. 191-214 ◽  
Author(s):  
Elic M. Weitzel
Keyword(s):  
North America ◽  
Optimal Foraging Theory ◽  
River Valley ◽  
Foraging Efficiency ◽  
Eastern North America ◽  
Human Populations ◽  
Tennessee River ◽  
Tennessee River Valley ◽  
Middle Tennessee ◽  
Relationship Of

Recently, researchers investigating the origins of domestication have debated the significance of resource intensification in the shift from foraging to food production. In eastern North America, one of several independent centers of domestication, this question remains open. To determine whether initial domestication may have been preceded by intensification in eastern North America at approximately 5000 cal BP, I evaluated the archaeofaunal assemblages from six sites in the middle Tennessee River valley. Analyses of these data suggest that overall foraging efficiency gradually declined prior to initial domestication, but patch-specific declines in foraging efficiency occurred in wetland habitats and not terrestrial ones. Climatic warming and drying during the Middle Holocene, growing human populations, and oak-hickory forest expansion were the likely drivers of these changes in foraging efficiency. These results support the hypothesis that initial domestication in eastern North America was an outcome of intensification driven by environmental change and human population increases. Finally, while the debate concerning the relationship of intensification to domestication has been framed in terms of a conflict between niche construction theory and optimal foraging theory, these perspectives are compatible and should be integrated to understand domestication more fully.

scholarly journals A Chlorophyll Fluorescence Screening Test to Evaluate Chilling Tolerance in Tomato

HortScience ◽  
1990 ◽  
Vol 25 (3) ◽  
pp. 334-339 ◽  
Author(s):  
Mark A. Walker ◽  
Dale M. Smith ◽  
K. Peter Pauls ◽  
Bryan D. McKersie
Keyword(s):  
Chlorophyll Fluorescence ◽  
Low Temperature ◽  
Lycopersicon Esculentum ◽  
Temperature Stress ◽  
Low Temperatures ◽  
Screening Test ◽  
Full Range ◽  
Chilling Tolerance ◽  
Solanum Lycopersicoides ◽  
Commercial Cultivars

The chilling tolerance of commercial Lycopersicon esculentum cultivars (H2653, H722), Solanum lycopersicoides, an F1 hybrid of S. lycopersicoides × Sub-Arctic Maxi, and 25 BC2F2 lines of L. hirsutum × H722 (backcrossed twice to H722) was evaluated using a chlorophyll fluorescence assay. The ratio of the initial to the peak fluorescence (Fo: Fp) measured from fully expanded leaves was chosen as an indicator of plant health. Chilling induced an increase in Fo: Fp that was correlated with the sensitivity of the plant to low-temperature stress. Values of Fo: Fp remained low for cold-treated S. lycopersicoides and the F1 hybrid, which showed few symptoms of chilling-related damage, whereas the commercial cultivars, which were essentially intolerant to low temperatures, had large increases in Fo: Fp. A full range of Fo: Fp values was measured in the 25 BC2F2 lines, indicating that some chilling tolerance from the L. hirsutum parent was expressed by plants in these populations.

The influence of light and diurnal freezing temperature on the cold hardiness of winter wheat seedlings

1974 ◽  
Vol 52 (12) ◽  
pp. 2539-2546 ◽  
Author(s):  
C. J. Andrews ◽  
M. K. Pomeroy ◽  
I. A. de la Roche
Keyword(s):  
Low Temperature ◽  
Winter Wheat ◽  
Filter Paper ◽  
Cold Hardiness ◽  
Freezing Temperature ◽  
Wheat Seedlings ◽  
Temperature Growth ◽  
Low Temperature Growth

Seedlings of winter wheat (Triticum aestivwn cv. Rideau and Cappelle Desprez) grown on moist filter paper in petri plates in dark at low temperature increased in cold hardiness, as measured by changes in the LD50 temperatures. Rideau attained an LD50 temperature of −12 °C after 5 weeks, Cappelle Desprez, −6 °C. Exposure to light delayed the maximum hardiness by 2 weeks and increased it by 6 °C in both cultivars. Exposure to diurnal freezing temperature increased hardiness of both cultivars in the dark, and in light when excessive dehydration was prevented.Greater cold hardiness of plants of both cultivars was attained in soil in light at low temperature as compared with those in petri plates. Exposure of plants to diurnal freezing temperature maintained a higher level of hardiness after the maximum at 7 weeks than continuous low temperature without freezing. Diurnal freezing during active low temperature growth in petri plates or in soil increased hardiness of Rideau seedlings to an apparent maximum of −18 °C.

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