In tobacco, optimum temperature is around 25°C. Pollen embryos are not formed in D. innoxia anthers cultured at 20°C or below. Clearly temperature optimum varies with the species. In some species, e.g., grape, potato, Datura, etc., exposure of anthers to light during their first 24 hr of culture enhances the frequency of haploid callus or responding anthers. Light appears to be beneficial even in those species where anthers cultured in dark respond adequately. Isolated pollen grains require a relatively low intensity of light.
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