Long-lasting light effects in imbibed Kalanchoe blossfeldiana seeds in the presence of gibberellic acid
1990
Rethy, R. | Dedonder, A. | Cappelle, M. | Fredericq, H. | Greet, J. de
Two brief red (R) irradiations, separated by 24 hours, given to Kalanchoe blossfeldiana Poelln. cv Feuerblute seeds, made secondarily dormant by a prolonged dark incubation period on water and transferred to GA3, induce very low germination. Some effect of these irradiations is preserved, however, during a long dark interval in fully imbibed seeds and greatly increases the germination induced by another brief R exposure. This long-lasting light effect is, at 20 degrees C, only lost after a dark interval of about 1 month. it can also be induced by two brief far-red (FR) exposures. its preservation is temperature-dependent, low temperatures being favorable. Light-induced changes in the ATP-content were demonstrated during preservation and expression of the long-lasting light effect, indicating a long-lasting metabolic change. In seeds with primary dormancy sown on GA3, an analogous long-lasting light effect is induced by one or two brief R or FR irradiations, even when they are given before germination can take place. The presence of GA3, which was shown to induce a very low fluence germination response in Kalanchoe seeds, is required for the occurrence of the long-lasting light effect. The data suggest long-term preservation of some effect(s) of Pfr rather than persistent presence of Pfr itself.
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