scholarly journals Low-temperature Tolerance of Testing Woody Ornamental Plants: A Comparison of Ice-seeded vs. Nonseeded Methodologies

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 508E-508
Author(s):  
Paul E. Cappiello ◽  
John F. Wachter ◽  
B. Libby
Keyword(s):  
Low Temperature ◽  
Ornamental Plants ◽  
Testing Procedure ◽  
Temperature Tolerance ◽  
Evergreen Species ◽  
Low Temperature Tolerance ◽  
The Difference ◽  
The Many ◽  
Controlled Freezing

Accurate assessment of the low-temperature tolerance of woody landscape plants is essential to ensure proper siting and use of specific varieties in the landscape. Laboratory determination of lowest survival temperature (LST) has become a popular area of study in recent years, yet there has been no standardization of technique among the many labs conducting this work. One of the major differences in technique employed across the country is the presence or absence of ice seeding of samples prior to the testing procedure. This presentation will present results of a series of studies conducted to determine the need for and efficacy of ice seeding treatments for LST determination in woody plants. A series of four studies was conducted over a 3-year period to test the difference in LST estimation with and without ice seeding. Twenty-two taxa, including both deciduous and evergreen species, were subjected to controlled freezing at ≈4°C/hr. with test samples removed from the freezer every 3°C. Following a 24-hr thaw and 5 to 7 days of incubation at 21°C, 100% RH, stems were sliced longitudinally and visually assessed for damage to vascular tissues. In the majority of cases, ice seeding was determined to have no significant affect on LST determination. In several species (Kalmia latifolia, Vaccinium angustifolium), the introduction of ice seeding into the protocol resulted in greater variation and less distinct determination of LST.

scholarly journals Lowest Survival Temperature (LST) Estimations in 33 Varieties of Viburnum by Controlled Freezing

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 579e-579
Author(s):  
John F. Wachter ◽  
Paul E. Cappiello
Keyword(s):  
Low Temperature ◽  
Temperature Tolerance ◽  
Visual Observation ◽  
Stem Cuttings ◽  
Low Temperature Tolerance ◽  
Cold Tolerant ◽  
Controlled Freezing

Stems of 33 varieties of Viburnum were screened for low temperature tolerance on five dates. Terminal stem cuttings were shipped overnight to Orono, Maine, from Oregon, Michigan, and Minnesota. Following a controlled freezing regime, stems were incubated for 7–14 days and evaluated for injury by visual observation. Lowest survival temperatures (LST) were estimated as the lowest temperature at which 100% of stems were uninjured. Varieties of V. dentatum, V. lantana, V. opulus, and V. trilobum were rated as consistently very cold tolerant. Viburnum ×pragense, V. dilatatum, and V. rufidulum were rated as consistently moderately cold tolerant. All V. tomentosum varieties showed inconsistent LST estimates. Varieties from the Oregon source were rated as cold intolerant. Direct comparisons by variety and source will be discussed with emphasis on consistent LST estimates. Rates of deacclimation as they occurred over the five testing dates will also be discussed.

scholarly journals Low Temperature Tolerance of Zoysiagrasses

HortScience ◽  
1999 ◽  
Vol 34 (1) ◽  
pp. 96-99 ◽  
Author(s):  
J.H. Dunn ◽  
S.S. Bughrara ◽  
M.R. Warmund ◽  
B.F. Fresenburg
Keyword(s):  
Low Temperature ◽  
Field Study ◽  
Temperature Tolerance ◽  
Early Years ◽  
Winter Survival ◽  
Low Temperature Tolerance ◽  
Shoot Number ◽  
Freezing Test ◽  
Controlled Freezing ◽  
Shoot Mass

Rhizomes of zoysiagrass (Zoysia spp.) were subjected to controlled freezing tests in Jan. and Mar. 1993 and 1994 to determine their low-temperature tolerance. In 1994, `Belair', `Korean `Common', `Meyer', and `TGS-W10' rhizomes survived temperatures as low as -18 °C, while rhizomes of `Sunburst' survived -14 °C. `Cavalier', `Crowne', `Palisades', `Emerald', and `El Toro' were killed at -10 °C or warmer temperatures. Entries surviving exposure to -14 to -18 °C in 1994 controlled freezing tests received post-winter survival ratings in the field of 6.7 to 8.7 (9 = 100% green). Entries killed at higher freezing test temperatures were slower to recover after winter in the field, with ratings of 2.0 to 3.0. Shoot number produced after freezing was a better measurement for assessing low temperature tolerance than was shoot mass. Controlled freezing tests, using regrowth as a measure of hardiness, appear to be useful for identifying low temperature tolerance of zoysiagrasses in the early years of a field study.

scholarly journals Lowest Survival Temperature (LST) Estimations in Kalmia, Viburnum, and Magnolia by Controlled Freezing

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 508D-508
Author(s):  
John F. Wachter ◽  
Paul E. Cappiello
Keyword(s):  
Low Temperature ◽  
Test Temperature ◽  
Temperature Tolerance ◽  
Stem Cuttings ◽  
Kalmia Latifolia ◽  
Low Temperature Tolerance ◽  
Cold Tolerant ◽  
Controlled Freezing

Stems of 38 varieties of Kalmia latifolia, 33 varieties of Viburnum, and 45 varieties of Magnolia were screened for low-temperature tolerance on eight dates during the winters of 1995–96 and 1996–97. Terminal 6- to 8-cm stem cuttings were shipped overnight on ice to Orono, Maine, and processed immediately upon arrival. Cuttings were subjected to a controlled freezing regime with a lowest test temperature ranging from –31°C to –42°C. Following freezing, stems were incubated for 5 to 14 days at 21°C and evaluated for injury. Lowest survival temperatures (LST) for each variety were estimated as the lowest temperature at which 100% of stems were undamaged. Varieties of Viburnum dentatum, V. lantana, V. opulus, and V. trilobum were rated as consistently very cold-tolerant, with LSTs of at least –36°C on all test dates. All V. plicatum var. tomentosum varieties showed inconsistent survival and LST estimations. Midwinter LST estimates in Kalmia latifolia showed 40% of the tested varieties remained undamaged at or below –36°C. Ten percent of K. latifolia varieties tested were damaged at –24°C or warmer, with the remaining varieties having LSTs somewhere between –24°C and –40°C. Varieties of Magnolia showed inconsistent survival with LSTs estimated for only 5% of those tested. Direct comparisons by variety, test date and source will be discussed with emphasis on consistent LST estimation. Varieties of K. latifolia, Viburnum, and Magnolia best suited for use in northern landscapes will also be discussed.

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