scholarly journals Cold Hardiness of Floral Buds of Deciduous Azaleas: Dehardening, Rehardening, and Endodormancy in Late Winter

2007 ◽  
Vol 132 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Scott R. Kalberer ◽  
Rajeev Arora ◽  
Norma Leyva-Estrada ◽  
Stephen L. Krebs
Keyword(s):  
Water Content ◽  
Cold Hardiness ◽  
Late Winter ◽  
Chilling Requirement ◽  
Early Winter ◽  
Freeze Injury ◽  
Woody Perennials ◽  
Freeze Thaw ◽  
Floral Buds ◽  
Chilling Units

Dehardening resistance and rehardening capacity in late winter and spring are important factors contributing to the winter survival of woody perennials. Previously the authors determined the midwinter hardiness, dehardening resistance, and rehardening capacities in deciduous azalea (Rhododendron L.) floral buds in early winter. The purpose of this study was to investigate how these parameters changed as winter progressed and to compare rehardening response at three treatment temperatures. Experiments were also conducted to measure bud water content during dehardening and chilling accumulation of 10 azalea genotypes. Buds of R. arborescens (Pursh) Torr., R. canadense (L.) Torr., R. canescens (Michx.) Sweet, and R. viscosum (L.) Torr. var. montanum Rehd. were acclimated in the field and were dehardened in the laboratory at controlled warm temperatures for various durations. Dehardened buds were rehardened for 24 hours at 2 to 4 °C, 0 °C, or –2 °C. Bud hardiness (LT50) was determined from visual estimates of freeze injury during a controlled freeze–thaw regime. The midwinter bud hardiness in the current study was ≈4 to 8 °C greater than in early winter. R. canadense and R. viscosum var. montanum dehardened to a larger extent in late winter than in the early winter study whereas R. arborescens and R. canescens did not. The rehardening capacities were larger in early than in late winter. Even though rehardening occurred throughout the first 8 days of dehardening (DOD) in early winter in the previous study, in the current study it was only observed after 10 DOD (R. viscosum var. montanum) or 15 DOD (R. arborescens). There was no difference among the rehardening capacities at the three rehardening temperatures for any genotype. Water content decreased throughout dehardening in all four genotypes examined. R. canadense had the lowest chilling requirement (CR) [450 chilling units (CU)], followed by R. atlanticum (Ashe) Rehd., R. austrinum (Small) Rehd., R. canescens, and R. calendulaceum (Michx.) Torr. with intermediate CR [820, 830, 830, and 1000 CU respectively). The CR of R. arborescens, R. prinophyllum (Small) Millais, R. prunifolium (Small) Millais, R. viscosum var. montanum, and R. viscosum var. serrulatum (Small) Millais exceeded 1180 CU. Results of this study indicate that the dehardening kinetics (magnitude and rate) and the rehardening capacity of azalea buds are influenced by the progression of winter and the depth of endodormancy.

scholarly journals Cold Hardiness, Deacclimation Kinetics, and Bud Development among 12 Diverse Blueberry Genotypes under Field Conditions

2005 ◽  
Vol 130 (4) ◽  
pp. 508-514 ◽  
Author(s):  
Lisa J. Rowland ◽  
Elizabeth L. Ogden ◽  
Mark K. Ehlenfeldt ◽  
Bryan Vinyard
Keyword(s):  
Cold Hardiness ◽  
Frost Tolerance ◽  
Winter Hardiness ◽  
Field Conditions ◽  
Pearl River ◽  
Late Winter ◽  
Genotypic Differences ◽  
Strong Positive Correlation ◽  
Spring Frost ◽  
Woody Perennials

Deacclimation response is an important part of reproductive success in woody perennials because late winter or early spring thaws followed by hard freezes can cause severe injury to dehardened flower buds. There is a need to develop more spring-frost tolerant cultivars for the blueberry (Vaccinium L.) industry. The identification of later or slower deacclimating genotypes could be useful in breeding for more spring-frost tolerant cultivars. This study was undertaken to investigate cold hardiness and deacclimation kinetics under field conditions for 12 Vaccinium (section Cyanococcus A. Gray) genotypes (the cultivars Bluecrop, Duke, Legacy, Little Giant, Magnolia, Northcountry, Northsky, Ozarkblue, Pearl River, Tifblue, and Weymouth; and a population of V. constablaei Gray) with different germplasm compositions and expected mid-winter bud hardiness levels. Examination of bud cold hardiness (BCH) vs. weeks of deacclimation over a 7-week period in 2 consecutive years (2002 and 2003) revealed clear genotypic differences in cold hardiness and timing and rate of deacclimation. Among cultivars, `Legacy' was the least cold hardy at initial evaluation, even less so than `Tifblue'. Regarding deacclimation kinetics, the weekly intervals with the largest losses (i.e., high rates of deacclimation) also varied among genotypes. For `Duke', the largest losses in BCH were detected at weeks 2 and 3, making it the earliest deacclimator. For `Bluecrop', `Ozarkblue', `Weymouth', `Tifblue', and `Legacy', the greatest losses in BCH were observed at weeks 3 and 4. For `Little Giant', `Magnolia', `Northcountry', `Northsky', and `Pearl River', losses in BCH were greatest at weeks 4 and 5, while for V. constablaei, losses were greatest at weeks 6 and 7, making it the latest deacclimator. Deacclimation kinetics were not correlated with mid-winter hardiness or chilling requirements in any fixed pattern. On the other hand, a strong positive correlation was found between BCH and stage of bud opening (r = 0.84). A comparison of timing of deacclimation with germplasm composition indicated that V. constablaei was particularly late to deacclimate. `Little Giant', a 50:50 hybrid of V. constablaei and V. ashei Reade, was nearly as late to deacclimate as the 100% V. constablaei selections. Thus, V. constablaei may be useful in breeding programs to contribute genes for late deacclimation, which should translate into greater spring frost tolerance, in addition to genes for mid-winter hardiness.

scholarly journals 335 Juvenility Influences Cold Acclimation Ability in Rhododendron Populations

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 500F-501
Author(s):  
Chon C. Lim ◽  
Rajeev Arora ◽  
Stephen L. Krebs
Keyword(s):  
Woody Plants ◽  
Cold Hardiness ◽  
Genetic Factors ◽  
Ion Leakage ◽  
Juvenile Period ◽  
Woody Perennials ◽  
Freeze Thaw ◽  
Age Dependent ◽  
Period Data ◽  
The Relationship

Winter survival in woody plants is controlled by environmental and genetic factors that affect the plant's ability to cold-acclimate. A juvenile period in woody perennials raises the possibility of differences in cold-acclimating ability between juvenile vs. mature (flowering) phases. This study investigated the yearly cold hardiness (CH) changes of rhododendron populations and examined the relationship between leaf freezing tolerance (LFT) and physiological aging. Naturally acclimated leaves (January) from individual plants (parents-R. catawbiense and R. fortunei, F1, F2, and backcross) and F1 population generated from R. catawbiense and R. dichroanthum cross were subjected to controlled freeze-thaw regimes. LFT was assessed by measuring freeze-thaw-induced ion leakage from leaf discs frozen over a range of treatment temperatures. Data were then plotted with a sigmoidal (Gompertz) curve by SAS, to estimate Tmax—the temperature causing maximum rate of injury. Tmax for the 30- to 40-year-old parental plants (catawbiense, fortunei, and dichroanthum) and the F1 `Ceylon' (catawbiense × fortunei) were estimated to be about -52, -32, -16, and -43 °C, respectively. These values were consistent over the 3-year evaluation period. Data indicated the F2 (50 seedlings) and backcross (20 seedlings) populations exhibited significant, yearly Tmax increment (of ≈5-6 °C) from 1996 to 1998 as they aged from 3 to 5 years old. A similar yearly increase was observed in the 12 F1 progenies (compared 2 to 3 years old) of catawbiense × dichroanthum cross. The feasibility of identifying hardy phenotypes at juvenile period and research implications of age-dependent changes in CH will be discussed.

Seasonal Water Content and Distribution in Eastern White Pine

1969 ◽  
Vol 45 (1) ◽  
pp. 38-43
Author(s):  
S. N. Linzon
Keyword(s):  
Water Content ◽  
Pinus Strobus ◽  
Late Winter ◽  
Early Winter ◽  
White Pine ◽  
Eastern White Pine ◽  
Seasonal Rhythm ◽  
Late Autumn ◽  
Early Autumn

Studies over a 30-month period revealed the presence of a seasonal rhythm in water content in the sapwood and in wet and dry portions of the heartwood of eastern white pine, Pinus strobus L. The data, indicated an increase in water content in late autumn and early winter, a drying out in late winter, a slight increase in the spring, fluctuations during the summer strongly influenced by weather, and a slight decrease in early autumn prior to the increase at the end of the year. The newest parts of the crown were the wettest in the tree. Outer rings in the sapwood of the crown were wetter than those in the bole and butt. Wet heartwood possessed as high a water content as sapwood, whereas dry heartwood contained the lowest water content of all the parts of the tree examined.

scholarly journals Pruning Effects on the Cold Hardiness of `Haggerston Gray' Leyland Cypress and `Natchez' Crape Myrtle

HortScience ◽  
1991 ◽  
Vol 26 (11) ◽  
pp. 1381-1383 ◽  
Author(s):  
C.L. Hayns ◽  
O.M. Lindstrom ◽  
M.A. Dirr
Keyword(s):  
Cold Hardiness ◽  
Late Summer ◽  
Early Spring ◽  
Late Winter ◽  
Early Winter ◽  
Maximum Difference

The effects of late summer, fall, and winter pruning on the cold hardiness of × Cupressocyparis leylandii (A.B. Jacks. and Dallim.) Dallim. and A.B. Jacks. `Hag gerston Gray' (Leyland cypress) and Lagerstroemia L. `Natchez' (crape myrtle) were determined. Pruning in late summer through early winter significantly reduced the cold hardiness of both taxa. The maximum difference in cold hardiness between pruned trees and controls for × Cupressocyparis leylandii `Haggerston Gray' in October, December, January, and February was 3, 3, 2, and 6C, respectively. The maximum difference in cold hardiness between pruned plants and controls for Lagerstroemia `Natchez' in December, January, and February was 3, 4, and 2C, respectively. Early spring pruning of Leyland cypress and late winter or early spring pruning of crape myrtle are suggested from these data.

scholarly journals Use of Blueberry to Study Genetic Control of Chilling Requirement and Cold Hardiness in Woody Perennials

HortScience ◽  
1999 ◽  
Vol 34 (7) ◽  
pp. 1185-1191 ◽  
Author(s):  
Lisa J. Rowland ◽  
Elizabeth L. Ogden ◽  
Rajeev Arora ◽  
Chon-Chong Lim ◽  
Jeffrey S. Lehman ◽  
...  
Keyword(s):  
Genetic Control ◽  
Cold Hardiness ◽  
Chilling Requirement ◽  
Woody Perennials

scholarly journals Cold Hardiness of Weigela Cultivars

1998 ◽  
Vol 16 (4) ◽  
pp. 238-242 ◽  
Author(s):  
Steve McNamara ◽  
Harold Pellett
Keyword(s):  
Low Temperature ◽  
Cold Hardiness ◽  
Temperature Tolerance ◽  
Cold Injury ◽  
Late Winter ◽  
Freeze Thaw ◽  
Lethal Temperatures ◽  
Low Temperature Tolerance ◽  
Temperature Controlled ◽  
Cold Hardy

Abstract Laboratory freezing tests of stem hardiness were conducted to develop cold hardiness profiles for 18 weigela (Weigela sp.) cultivars during the fall and winter of 1994–95. Tests were performed on containerized plants held in a temperature-controlled greenhouse to prevent exposure to potentially lethal temperatures. No cultivar survived below −6C (21F) in the October 3 test. Subsequent differences in rates of acclimation resulted in cultivars differing in hardiness by as much as 13C (23F) on November 14. Taxa also differed greatly in their maximum midwinter low temperature tolerance with ‘Centennial’ and ‘Eva Supreme’ hardy to −44C (−47F) and −28C (−18F) in mid-January, respectively. None of the cultivars deacclimated substantially in response to a week of artificially-imposed diurnal freeze/thaw cycles in early February. Taxa with the greatest midwinter hardiness also maintained the greatest hardiness in early March. Overall, ‘Centennial’, ‘Java Red’, and ‘Samba’ were the most cold hardy cultivars tested, while ‘Boskoop Glory’, ‘Bristol Snowflake’, and ‘Variegata’ were the least hardy. Cold injury of susceptible weigela cultivars appears to be a consequence of late hardening and/or insufficient midwinter hardiness rather than rapid deacclimation in response to periods of warm temperatures in mid-to late-winter.

Stem Cold Hardiness, Leaf Heat Tolerance, Growth, and Performance of Six Japanese Maples (Acer palmatum) in Northern Illinois

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 512e-512
Author(s):  
A.M. Shirazi
Keyword(s):  
Water Content ◽  
Heat Tolerance ◽  
Cold Hardiness ◽  
Block Design ◽  
Leaf Tissue ◽  
Ion Leakage ◽  
Randomized Block Design ◽  
Leaf Tissues ◽  
Artificial Freezing ◽  
And Performance

Six different Japanese Maples (Acer palmatum) cultivars `Water Fall', `Burgundy Lace', `Crimson Queen', `Oshio-Beni', `SangoKaKu', and `Bloodgood' from Monrovia Nursery were planted in a randomized block design on 4 June 1997 at the The Morton Arboretum. Leaf heat tolerance was evaluated by measuring ion leakage of the leaf tissue at 25–60 °C in July, Aug., and Sept. 1997. The LT50 (the temperature at which 50% of the tissues were injured) of all the cultivars were higher in July (≈53 °C) and were lower in September (≈47 °C). Water content of the leaf tissues were higher in July compare to August and September and were not related to heat tolerance of most cultivars. Stem cold hardiness was performed by artificial freezing tests in Oct., Dec., and Feb. 1997/98. The Lowest Survival Temperature (LST) for the most hardy to least hardy cultivars in October and December were: `Burgundy Lace' (–15, –27 °C), `Bloodgood' (–18, –24 °C), `Oshio-Beni' (–15, –24 °C), `Crimson Queen' (–15, –18 °C), `Water Fall' (–9, –18 °C) and `SangoKaKu' (–9, –12 °C), respectively. Growth, dormancy development, spring budbreak and performance of these cultivars will be compared.

scholarly journals Influence of Northern Hemispheric Winter Warming on the Pacific Storm Track

2021 ◽  
Author(s):  
Hyung-Ju Park ◽  
Kwang-Yul Kim
Keyword(s):  
Heat Flux ◽  
Global Warming ◽  
Energy Conversion ◽  
Storm Track ◽  
The Arctic ◽  
Late Winter ◽  
Turbulent Heat ◽  
Early Winter ◽  
Eddy Heat Flux ◽  
Northern Hemispheric

AbstractEffect of global warming on the sub-seasonal variability of the Northern Hemispheric winter (NDJFM) Pacific storm-track (PST) activity has been investigated. Previous studies showed that the winter-averaged PST has shifted northward and intensified, which was explained in terms of energy exchange with the mean field. Effect of global warming exhibits spatio-temporal heterogeneity with predominance over the Arctic region and in the winter season. Therefore, seasonal averaging may hide important features on sub-seasonal scales. In this study, distinct sub-seasonal response in storm track activities to winter Northern Hemispheric warming is analyzed applying cyclostationary empirical orthogonal function analysis to ERA5 data. The key findings are as follows. Change in the PST is not uniform throughout the winter; the PST shifts northward in early winter (NDJ) and intensifies in late winter (FM). In early winter, the combined effect of weakened baroclinic process to the south of the climatological PST and weakened barotropic damping to the north is responsible for the northward shift. In late winter, both processes contribute to the amplification of the PST. Further, change in baroclinic energy conversion is quantitatively dominated by eddy heat flux, whereas axial tilting of eddies is primarily responsible for change in barotropic energy conversion. A close relationship between anomalous eddy heat flux and anomalous boundary heating, which is largely determined by surface turbulent heat flux, is also demonstrated.

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