The effects of activated charcoal and organic substances on embryogenesis in anther cultures of Anemone canadensis L. were studied. Embryogenesis was independent of the presence in the culture medium of glycine, nicotinic acid, pyridoxine, thiamine, folic acid, d‐biotin or myoinositol. Absence of Fe‐EDTA totally inhibited embryogenesis. Activated charcoal (AC) adsorbed Fe‐EDTA, pyridoxine, folic acid and nicotinic acid in a double‐layer medium almost completely within 24 h. If petri dishes according to the souble‐layer method were stored overnight or more, embryogenesis was totally inhibited, probably due to adsorbtion of Fe‐EDTA by AC. It was shown that AC itself released some yet unidentified substance(s) that stimulated embryogenesis. The addition of polyvinylpolypyrrolidone (PVPP) to the culture medium stimulated embryogenesis, but PVPP was not as efficient as AC. Embryogenesis was totally inhibited when AC and PVPP were applied together. Minor additions of ethanol to the culture medium stimulated embryogenesis when AC was present, but no such effect was obtained when AC was absent.

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Four tetraploid potato genotypes (194.10, 199.13, 201.5, 201.12) were examined in anther culture. The androgenic responses were in general high. Cv. 199.13 contributed with the best response, varying between 0.38 and 0.55 embryoids per anther. Gellan gum or potato starch were used as gelling agents in a double-layer medium. Anthers incubated on potato starch gave a higher embryo yield in the beginning of the culture period, compared to anthers cultivated on gellan gum. The number ofembryoids per anther, however, was higher on gellan gum at the end of the culture period. Anther cultures of potato were incubated in two different temperatures (20 °C and 25 °C), and the highest embryo yield was obtained in 25 °C except for genotype 201.12 where no difference was found between the two temperatures. Experiments with pollen germination in various temperatures (10 °C and 20 °C) were correlated to anther culture experiments. Also in case of pollen germination, genotype 201.12 was temperatureindependent, while germination was stimulated by higher temperatures in the other genotypes.

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