Low temperature exotherms of winter buds of hardy conifers |
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Authors: | Sakai Akira |
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Institution: | The Institute of Low Temperature Science, Hokkaido University Sapporo 060, Japan |
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Abstract: | Differential thermal analysis (DTA) of winter buds and the excisedprimordial shoots of sub-alpine or sub-cold firs revealed thatthese buds had all low temperature exotherms around 30?C.However, no low temperature exotherm below 15?C was detectedin the spring buds. In the winter bud of Abies firma, a temperatefir native to Japan, a low temperature exotherm was detectedaround 20?C, which is higher by 10?C than that of sub-alpineor sub-cold firs. The low temperature exotherms of these firsoccurred at nearly the same temperatures that result in thedeath of these primordial shoots. On the other hand, littleor no low temperature exotherm was detected in the winter budsof sub-cold spruces. In larch winter buds, numerous small exothermswere observed, which are probably due to the many leaf primordiain the buds. Unlike many temperate deciduous broad-leaved trees,no low temperature exotherm was detected below 15?C inwinter twig xylem of conifers such as Abies, Picea, Pinus, Larixand Pseudotsuga. Thus, very hardy coniferous twigs can tolerateextracellular freezing to 70?C.
1 Contribution No. 1907 from the Institute of Low TemperatureScience. (Received June 8, 1978; ) |
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