Influence of sowing time and chilling exposure on flower induction in carrot (Daucus carota L.)

Carrot (Daucus carota L.) is a cool-season vegetable normally classified as a biennial species, requiring vernalisation to induce flowering. Generally, for seed production in France, the technique used is seed-to-seed, with sowing in August and harvest in August the next year. The quality of flowering, expressed in percentage of plants induced, depends on different parameters such as the genotype, the stage of development and chilling exposure. We have compared two different genotypes from open-pollinated cultivars, the first one is considered susceptible to flowering, 'Blanche à collet vert très hors terre', and the second one, 'Carol', less susceptible. For two years, 2012 and 2013, different sowings were compared for different seed lots coming from early or late flowering dates. Plants from seeds from the earliest flowering carrots flowered at an earlier stage of development and with a lower chilling requirement. Only one cycle is necessary to induce this difference.