Morphological, physical and physiological changes during maturation and ripening of ash (Fraxinus excelsior L.) seeds

The establishment of certain morphological, physical and physiological criteria was considered and this might allow us to determine more precisely the maturation degree as well as the optimum harvest and sowing period of seeds. The criteria for assessing the maturation degree of seeds presented earlier (the completely formed embryo, the prominent endosperm with a normal consistency) can now be completed with a new criterion, namely the one referring to the slight tendency of the seesds tegument to get yellow. This is due to the fact that the seed completes its growing sooner than the pericarp. The fact was proved both by the greater decrease the fresh mass of the pericarp than that of the seed and by the greater decrease of the moisture content of the seed than that of the pericarp during the four examined ripening phases.