Embryos of the moss Aloina ambigua are inducibly desiccation tolerant (DT), requiring a slow-dry period to confer tolerance to air-dryness. Hardening to DT describes a condition of temporary tolerance to a rapid-dry event (<30 min from full turgor to air-dryness) that is conferred by a prior slow-dry event.
Brinda et al. found for the first time that moss embryos can indeed be hardened to DT, by first slowly drying embryos and equilibrating them at 50 % relative humidity, then rehydrating the embryos and exposing them to a rapid dry event at intervals of 24 h. The degree of hardening to DT is dependent upon the prior rate of slow-drying. Finally, a new metric for assessing DT is presented as the minimum rate of drying in order for shoots or embryos to recover undamaged upon rehydration.
Brinda, J. C., Stark, L. R., Clark, T. A., & Greenwood, J. L. (2015). Embryos of a moss can be hardened to desiccation tolerance: effects of rate of drying on the timeline of recovery and dehardening inAloina ambigua(Pottiaceae). Annals of Botany, 117(1), 153–163. http://dx.doi.org/10.1093/aob/mcv136