Comparison of three cold hardiness tests for conifer seedlings

Abstract

Greenhouse-cultured, container-grown ponderosa pine (Pinus ponderosa var. scopulorum Engelm.), interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco), and Engelmann spruce (Picea engelmannii (Parry) Engelm.) were cold acclimated and deacclimated in growth chambers over 19 weeks. Cold hardiness was measured weekly by a whole-plant freeze test and by two quick tissue tests: freeze-induced electrolyte leakage of needles, and differential thermal analysis of buds. The whole-plant freeze test provided results in 7 days, and indicated differences in cold hardiness among stems, buds, and needles. Although the whole-plant freeze test could accurately measure cold hardiness, it was not precise, and it required destructive sampling. Results from freeze-induced electrolyte leakage and differential thermal analysis were available in 2 days and 1 hour, respectively. The freeze-induced electrolyte leakage test was a precise, sensitive and objective predictor of changes or differences in tissue cold hardiness. To determine actual cold hardiness, results could be calibrated to the response of the same tissue in the whole-plant freeze test. The speed and objectivity of differential thermal analysis made this test useful for rapid, general assessment of cold hardiness status, but calibration was difficult, and precision varied.

Effects of excess nitrogen on frost hardiness and freezing injury of above‐ground tissue in young oaks (Quercus petraea and Q. robur)

“…In the present study, values of that magnitude were obtained in April, after a distinct increase in the minimum air temperature. These results represent an additional corroboration of the method and indicate its suitability for quantifying the state of frost hardiness in plant tissues (Alexander et al, 1984 ;Burr et al, 1990).…”

“…To assess the frost hardiness of plants, Flint et al (1967) suggested calculating an index of injury from the relative electric conductivities of solutions in which the samples had been incubated. This method has been widely adopted to test the frost hardiness of various parts of trees such as stem sections (van den Driessche, 1976), twigs (Alexander et al, 1984) and needles (Burr et al, 1990). More recently, Murray et al (1989) developed a method based on the rate of electrolyte leakage, which has been used successfully to quantify the freezing injury to woody shoots in, for example, Calluna vulgaris (Caporn et al, 1994), Quercus petraea (Deans et al, 1995) and Picea abies (Sheppard et al, 1995).…”

Fall fertilization of Pinus resinosa seedlings: nutrient uptake, cold hardiness, and morphological development

“…Compared to the whole plant freeze test, FIEL of needle samples yields a more precise, quick, sensitive, and objective predictor of changes or differences in tissue cold hardiness (Burr et al, 1990). Because one-year-old red pine seedlings have a small quantity of needles, needles were randomly selected along the entire length of the shoot, carefully detached from seedlings, and rinsed with distilled water.…”

Winter variation in physiological status of cold stored and freshly lifted semi-evergreen Quercus nigra seedlings

“…Samples were autoclaved (121 • C for 30 min) to achieve total cell death. Final conductivity readings were recorded after a second overnight leakage period (EC 2 ; following Burr et al, 1990). Blank vials were also measured and subtracted from EC 1 and EC 2 of each vial (Ritchie and Landis, 2003).…”