FROST HARDINESS OF RASPBERRY CANES

The observations showed, quite often, serious frost injury on raspberry plantation.
Since frost hardiness of raspberries seems to be related to their dormancy, this relationship was studied in four raspberry cultivars/cvs/: Canby, Latham, Malling Promise and Vetten.
The depth of dormancy was expressed by the number of developed buds on the canes, after 4 weeks of incubation in greenhouse; the lower the number the deeper was the dormancy.
There was also tested the effect of benzyladenine /BA/ and gibberellic acid /GA₃/ on the dormancy of raspberries.
During the deep dormancy of control canes, BA treatment slightly increased the percentage of developed buds, gibberellin effect was even stronger, but neither BA nor GA was able to break the dormancy /the cane is considered dormant, if less then 50 % of buds have developed after 4 weeks of incubation/. For all cvs. rest period lasted from October till late December.
Even though, the deep dormancy ceased in December, frost hardiness was still increasing, and it reached maximum level in February.
After maximum resistance was reached, there was observed a rapid decrease of hardiness.

It was found that abscisic acid /ABA/and BA increased frost hardiness of all tested raspberry cvs, except Vetten, when applied in late winter /2.02.1977/, by increasing the regeneration ability of canes after frost injury.
Those two growth regulators were not able to increase frost resistance, when applied in early spring /23.03/. The laboratory freeze-injury was determined, using growth test on mist propagation bench.

Symposium on Winterhardiness in Woody Perennials

B. Zraly

https://doi.org/10.17660/ActaHortic.1978.81.17