APPLE STEM CALLUS FROST TOLERANCE AND GROWTH MODIFICATION BY ADDING SORBITOL AND SOME GROWTH REGULATORS TO THE MEDIUM

It was found that replacing sucrose with sorbitol in the basic Murashige-Skoog /MS/ medium, a more prolific growth of the apple stem callus was obtained; and it increased its tolerance to -12.5°C, and -13.5°C. The callus grown on the medium with 3, 5, 8 % sucrose and 3 % sorbitol was killed when exposed to -15°C, whereas 50 % of that grown on 8 % sorbitol had survived.

In the spring of 1977 the first experiments on the effect of growth regulators /CCC, GA, Alar, ABA and Ethrel at conc. of 20 ppm/ on the frost tolerance of apple stem callus were made.
It was found that the addition of CCC and Alar to the medium inhibited the growth of the callus /figure 1/. Preliminary results with freezing the callus had indicated that ABA, Ethrel and Alar increased slightly the frost tolerance of apple callus but the re-growth of the callus in different flasks varied greatly, and the fresh weight of the callus could not be used as a reliable index of viability after temperature stress.

The regeneration potential of individual cells was studied in Petri dishes on semi-solid agar.
It became evident that small, young cells survived the exposure to -15°C better than the large, older cells /figure 2/.

In the future the experiments with above growth regulators will be repeated, and the regeneration potential after freezing of the dissociated callus cells studied.

Symposium on Winterhardiness in Woody Perennials

J. Pieniazek, T. Holubowicz, B. Machnik, M. Kasprzyk

https://doi.org/10.17660/ActaHortic.1978.81.10