ISHS Acta Horticulturae 585: VIII International Rubus and Ribes Symposium
CARBOHYDRATES AND WINTER HARDINESS IN RED RASPBERRY |
| Authors: | P. Palonen, O. Junttila |
| Keywords: | Acclimation, frost tolerance, hardening, in vitro, LT50, Rubus idaeus L., sucrose |
| Abstract:
Frequent winter injury to raspberry (Rubus idaeus L.) causes economic losses and is a primary limiting factor for expanding raspberry production in Finland. The objective of this study was to analyse the relationships between carbohydrates and cold hardiness in raspberry cultivars. Starch decreased, whereas soluble carbohydrates, especially sucrose, but also glucose, fructose, raffinose and stachyose accumulated during cold acclimation. A positive correlation between LT50 and starch, and negative correlations between LT50 and the amounts of soluble carbohydrates were established. High concentrations of total soluble carbohydrates and a high ratio of sucrose to glucose plus fructose were characteristic of a hardy cultivar under field conditions. Furthermore, the effect of exogenously applied sucrose on cold hardening of raspberry was examined. Raspberry plants (cv. 'Preussen') were cultured in vitro on MS media with sucrose levels of 1, 3, 5, and 7 %, and subjected to low temperature acclimation (3°/-3°C day/night) for 14 d. Exogenously applied sucrose was taken up by plants and amplified the effect of cold acclimation, 5 % sucrose in the culture medium being optimal for maximum cold hardening. Close correlations between total sugars, sucrose, glucose and fructose were established. After cold acclimation, plant osmolality predicted hardiness better than water content. The results demonstrated that sugars have more than a purely osmotic effect in protecting acclimated raspberry plants from cold. This study provided further evidence of the importance of carbohydrate reserves, especially sucrose, on winter survival of raspberry. To improve winter hardiness, cultural practices that enhance accumulation of carbohydrates in raspberry plants should be developed and tested. | |
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