Responses of Five Container-grown Herbaceous Perennial Species to Laboratory Freezing

The capacity of plant materials to resume normal growth after exposure to low temperature is the ultimate criterion of cold hardiness. We therefore determined the low-temperature tolerance of five commercially important herbaceous perennial species. Container-grown blanket flower (Gaillardia ×grandiflora Van Houtte. `Goblin'), false dragonhead [Physoste- gia virginiana (L.) Benth. `Summer Snow'], perennial salvia (Salvia ×superba Stapf. `Stratford Blue'), painted daisy (Tanacetum coccineum Willd. `Robinson's Mix'), and creeping veronica (Veronica repens Loisel.) were subjected to 0, -2, 4, -6, -8, -10, -12, -14, -16, and -18C in a programmable freezer. The percentage of survival of most species was adequate when exposed to -10C. Producers of container-grown perennials are advised to provide winter protection measures that prohibit root medium temperatures from falling below -10C.

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Cold Hardiness of Weigela Cultivars

Journal of Environmental Horticulture ◽

10.24266/0738-2898-16.4.238 ◽

1998 ◽

Vol 16 (4) ◽

pp. 238-242 ◽

Cited By ~ 1

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.

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Relationship between low-temperature tolerance and vernalization response in wheat and rye

Canadian Journal of Plant Science ◽

10.4141/cjps96-007 ◽

1996 ◽

Vol 76 (1) ◽

pp. 37-42 ◽

Cited By ~ 75

Author(s):

D. B. Fowler ◽

A. E. Limin ◽

Shi-Ying Wang ◽

R. W. Ward

Keyword(s):

Low Temperature ◽

Cold Hardiness ◽

Triticum Aestivum L ◽

Temperature Tolerance ◽

Temperature Acclimation ◽

Rate Of Change ◽

Curvilinear Relationship ◽

Vernalization Response ◽

Low Temperature Tolerance ◽

Winter Cereals

Vernalization response and low-temperature acclimation are survival mechanisms that cereals have evolved to cope with low-temperature stress. Both responses have similar optimum temperature ranges for induction, and they are controlled by genetic systems that are interrelated. It has also been suggested that the completion of vernalization is responsible for the gradual loss in low-temperature tolerance observed in winter cereals maintained for long periods of time at temperatures in the optimum range for low-temperature acclimation. In the present study, two experiments were conducted with the objective of clarifying the relationship between vernalization response and low-temperature tolerance in wheat (Triticum aestivum L.) and rye (Secale cereale L.). The plants of all cultivars began to low-temperature acclimate at a rapid rate when exposed to a constant 4 °C. The rate of change in low-temperature tolerance then gradually slowed and eventually started to decline, producing a curvilinear relationship between low-temperature tolerance and stage of acclimation. A close relationship was observed between the time to vernalization saturation and the start of the decline in low-temperature tolerance of cultivars held at 4 °C. However, cereal plants retained at least a partial ability to low-temperature acclimate following exposure to warm temperatures after vernalization saturation, indicating that vernalization saturation does not result in a "switching off" of the low-temperature tolerance genes. The possibility that vernalization genes have a more subtle regulatory role in the expression of low-temperature tolerance genes could not be ruled out, and future avenues for investigation are discussed. Key words: Cold hardiness, winter hardiness, cold resistance, low-temperature acclimation, deacclimation, vernalization, wheat, rye

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