Flowering initiation in plants of different Apiaceae species.

In this paper the action of flowering initiation is described as a multicomponent and multistep mechanism. This, without other endogenous and egzogenous factors, depends on solid action of photosynthesis, its primary metabolites and phytohormones. Our hypothesis is based on multifunctional flowering initiation model of biennial plants. The aim of this paper was to investigate the processes of juvenile period and flowering initiation; to evaluate the role of photosynthetic system; to describe the balance of phytohormones and sugars during morphogenesis in edible carrot (Daucus sativus (Hoffm.) Rohl.) and common caraway (Carum carvi L.). It was determined that the end of juvenile period in both carrot and caraway ontogenesis is related to formation of 9 assimilated leaves and with full competence to accept the stimulus of photo and thermo induction. Cold requirement for flower initiation in caraway is facultative therefore vernalization is not the main factor which strictly controls floral development. Active action of photosynthetic system and release of assimilates during evocation processes before flower initiation highlights the role of assimilates (especially of sucrose) in flowering initiation processes of Apiaceae plants. Synergistic interaction of ABA/GA3 and zeatin/IAA and antagonistic interaction of ABA/IAA determined the formation of flowering stem and flowering axis structures; however the development intensity depended on thermo and photoperiodic conditions.