Effect of water availability on spore germination of the moss Octoblepharum albidum from Brazilian Atlantic Forest

Abstract

Octoblepharum albidum generally produces sporophytes in the wet season and disperses spores in the dry season. Populations of this moss are found on tree bark in the edges of lowland tropical rainforests. When spores are dispersed during the drier months, they may be able to tolerate low water potentials on tree bark during germination. Thus, we investigated the effect of water potential on spore germination and early protonemal growth of the moss O. albidum from populations in a Brazilian lowland Atlantic Forest. We used water potentials of 0 to −1.46 MPa. Spores germinated at all water potentials tested, with ca 98% of germination at 2 −0.9 MPa. Mean time for germination was higher at −1.09 to −1.46 MPa (ca 16 days). Median base potential for germination (50%) of spores was −1.05 MPa, with spores germinating at −1.8 MPa according to the hydrotime model applied. The spores and the early protonemata of O. albidum are tolerant to water potentials lower than that measured in the field. This may help to explain the period of spore germination and the establishment of new plants during the dry season, as well as the wide occurrence of O. albidum in xeric habitats.