Ultrastructure of Carrot Seeds during Matriconditioning with Micro-Cel E

Matriconditioning (MC) of carrot seeds, with Micro-Cel E, improved their germinability by shortening the mean germination time and reducing the spread. Cytological studies indicated that the catabolic phase of germination sensu stricto advanced during the 8 d period of MC, but that the observed changes differed in embryo and endosperm tissues. Complete degradation of storage protein and lipid bodies, followed by starch accumulation were found to occur in the embryonic radicles of carrot seeds. In the endosperm, the catabolic changes were restricted to the micropylar area enclosing the radicle, where extensive breakdown of storage cell walls, partial degradation of protein bodies and no storage lipid hydrolysis were noted. The time course and localization of these changes suggested that weakening of the endosperm represented a secondary effect of priming, which was probably controlled and stimulated by the metabolically advanced embryonic axis. The benefits of seed matriconditioning have been explained on the basis of the fine structure observations.