Preliminary characterization of floral response of Xerophyta humilis to desiccation, vernalisation, photoperiod and light intensity

Xerophyta humilis is a monocotyledonous resurrection plant found in arid and semi-arid summer rainfall areas of Southern Africa, which undergoes desiccation to survive periods of extreme drought. In order for X.humilis to thrive in their natural habitat, correct timing of the floral transition, coincident with wet periods of sufficient duration, is essential. In this study, the environmental cues involved in the regulation of the floral transition in X.humilis were analysed. No single parameter tested was sufficient to induce flowering, but it was found that flowering was promoted by a combination of a cool period experienced while plants were hydrated, followed by transfer to long-day photoperiods of relatively high light intensity. Plants retained competence to flower if desiccated during exposure to cold, but no flowering occurred if dried prior to this exposure. These data suggest that exposure to cold temperature facilitates vernalisation and subsequent exposure to high light and long days are inductive for floral initiation in X. humilis.