ISHS Acta Horticulturae 560: IV International Symposium on In Vitro Culture and Horticultural Breeding
SUCROSE ENHANCES COLD HARDENING OF RASPBERRY PLANTS IN VITRO |
| Authors: | P. Palonen, O. Junttila |
| Keywords: | carbohydrates, cold acclimation, freezing test, LT50, Rubus idaeus |
| Abstract:
The influence of exogenously applied sucrose on cold hardening of raspberry (Rubus idaeus L.) in vitro was examined. Raspberry plants (cv. Preussen) were cultured on MS media with sucrose levels of 1, 3, 5 and 7%, and subjected to low temperature acclimation (3°/-3°C day/night temperature, 8 hour photoperiod) for 14 days. Cold hardiness (LT50 in controlled freezing), shoot moisture content, osmolality and the amounts of sucrose, glucose and fructose were determined. Exogenously applied sucrose was taken up by plants. Cold hardiness was primarily affected by acclimation treatment, but sucrose increased cold hardiness of non-acclimated plants and significantly enhanced the effect of acclimation treatment, 5% sucrose in culture medium being optimal for cold hardening. LT50 values ranged between -4.1° and -7.1°C for non-acclimated, and -14.2° to -20.7°C for cold acclimated shoots. After cold acclimation, plant osmolality was related to cold hardiness more closely than shoot moisture content. Increasing medium sucrose level increased plant sugar content, but cold acclimation had a stronger influence on sugar content. Sucrose, glucose and fructose accumulated during cold hardening. Close correlations between cold hardiness and total sugars, sucrose, glucose and fructose were established. Moreover, the results suggest that sugars have more than a purely osmotic effect in protecting acclimated raspberry plants from cold. | |
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