Cardinal Temperatures and Thermal Times for Vernalisation in Carrot cv. "Nantes"

Abstract

Effect of temperatures on bolting and flowering, measured as days to internode extension (bolting) and to flower bud visibility, respectively, were studied in carrot (Daucus carota) cultivar (cv.) "Nantes" grown in a controlled environment. All carrot plants raised from stecklings subjected to 10 weeks chilling at 3, 6 and 9 C bolted and flowered under subsequently warmer temperatures (18 C). However, only 33% of the stecklings given 1 and 12 C temperature pretreatments for a similar duration flowered. No flowering was observed for plants whose stecklings were pre-treated at 15 C for 10 weeks or those exposed to 1 C for 5 weeks. Plants chilled for 10 weeks required less days to bolting and flowering.