Harvest date, post-harvest vernalization and regrowth temperature affect flower bud induction in russian dandelion (Taraxacum kok-saghyz)

Abstract

Russian dandelion (Taraxacumkok-sagyz Rodin; TKS) is a promising candidate for introducing natural rubber production into North America; however, a comprehensive analysis of factors that influence flowering is essential for efficient breeding and crop development. The objectives of this study were to determine the effects of fall harvest date (early September, October and November), post-harvest vernalization (0, 4 and 8 wk at 48C), and greenhouse regrowth temperature [15/138C or 21/188C (day/night)] on flower induction. The vernalization requirements (0, 4, 8 and 12 wk at 48C) to reflower TKS plants were also examined in controlled environments at 21/188C. Plants harvested in September or October required 4 wk of vernalization and growth at 15/138C to maximize the percentage of plants with flower buds and minimize the time for flower bud appearance. Those harvested in November flowered quickly and at high frequency with no vernalization and regrowth at 21/188C. Vernalization was not essential to re-induce flowering; 80-100% of plants flowered regardless of treatment. Various combinations of harvest dates, vernalization periods and regrowth temperatures can be used to maximize flowering in TKS and have a positive impact on germplasm development.