The effects of temperature, photoperiod, and vernalization on regrowth and flowering competence in Euphorbia esula (Euphorbiaceae) crown buds

Abstract

The herbaceous perennial weed Euphorbia esula  L. (Euphorbiaceae) reproduces by vegetative and sexual means, characteristics that are key to its persistence and survival. In this study, we examined environmental effects on regrowth and flowering under controlled conditions to further validate field observations and set the stage for the future identification of molecular mechanisms involved in the regulation of these processes. Shoot cuttings were exposed to different combinations of decreasing temperatures, decreasing photoperiods, and vernalization, in growth chambers. Subsequently, shoots were removed and regrowth and flowering from new shoots were monitored in a warm temperature greenhouse under long-day conditions. Vernalization alone has no effect on regrowth and flowering. Plants required decreasing temperature followed by vernalization for rapid regrowth and flowering. Decreasing photoperiod at a constant temperature with or without vernalization had no significant effect on regrowth and flowering. In conjunction with previous field research, the results suggest that a gradually decreasing temperature is required as one of the components for flowering competence and vernalization is determinate for reproductive development under long-day conditions.