Vernalization Requirement, but Not Post-Vernalization Day Length, Conditions Flowering in Carrot (Daucus carota L.)

WOHLFEILER, JOSEFINA; ALESSANDRO, M.S.; MORALES, A.; CAVAGNARO, P. F.; GALMARINI, C.R.

Plants

MDPI

Lugar: Basilea; Año: 2022

2223-7747

Carrots require a certain number of cold hours to becomevernalized and proceed to the reproductive stage, and this phenomenon isgenotype-dependent. Annual carrots require less cold than biennials to flower;however, quantitative variation within annuals and biennials also exists, defininga gradient for vernalization requirement (VR). The flowering response ofcarrots to day length, after vernalization has occurred, is controversial. Thisvegetable has been described both as a long-day and a neutral-day species. Theobjective of this study was to evaluate flowering time and frequency inresponse to different cold treatments and photoperiod regimes in various carrotgenotypes. To this end, three annual genotypes from India, Brazil, andPakistan, and a biennial carrot from Japan, were exposed to 7.5 ◦C during 30,60, 90, or 120 days, and then transferred to either long day (LD) or short day(SD) conditions. Significant variation (p < 0.05) among the carrot genotypesand among cold treatments were found, with increased flowering rates andearlier onset of flowering being associated with longer cold exposures. Nosignificant differences in response to photoperiod were found, suggesting thatpost-vernalization day length does not influence carrot flowering. These findingswill likely impact carrot breeding and production of both root and seed,helping in the selection of adequate genotypes and sowing dates to manage coldexposure and day-length for different production purposes.