Carrot lowering initiation: light effect, photosynthetic pigments, carbohydrates

Abstract

The present study was aimed at the investigation of the influence of illumination spectrum on physiological processes in carrots (Daucus carota L.) during their evocation, flower initiation and differentiation. The process of flower initiation and morphogenesis was studied in a phytotron facility under treatment with different illumination spectra. The dominating 540-nm component and supplementary components {455-nm, 660-nm and 735-nm), High-performance liquid chromatography with a refractive-index detector was used for the detection and sepa-ration of carbohydrates. Total quantification of photosynthetic pigments was performed by spectrophotometric method. A considerable influence of illumination spectrum on physiological processes in the carrot, especially on the morphogenesis rate, was observed. We conclude that flower initiation processes in carrots can be controlled by tailoring the illumination spectrum and photon flux density. This enables one to accelerate plant cultivation in phytotron conditions. Conclusions: (t) The elimination of both red and far-red or only blue light appeared to suppress floral initiation, under such conditions carrots grew vegetative. In contrary, the elimination of solely far-red light resulted in faster flowering differention. (II) The elimination of solely red or blue light resulted in a low synthesis rate of photosynthetic pigments and conditioned high sucrose content in carrot root. Meanwhile, the elimination of solely far-red light resulted in the opposite effect. (III) Dominating 640-nm light was found toconsiderably contribute to the excitation of the carotenoid antennal complex of the photosynthetic system.