Distribution of micronutrients in maize grain and their mobilisation during germination

Abstract

The paper deals with the distribution and mobilisation of Fe, Mn, and Zn in various parts of maize grains (Zea mays L.). The highest initial concentrations of micronutrients were found in seed coat and embryo tissues, while the lowest ones were found in endosperm. The highest Zn concentrations were observed in embryo tissues. The total content of metals was higher in the endosperm. There were two stages of maize kernel germination, differing in the mobilisation patterns of micronutrients. During kernel imbibition (before radicle emergence) micronutrients leaked partially into the medium and then were reabsorbed by the seedling. The leakage of micronutrients depended on their initial concentration in the parts of the kernel. The endosperm was the main source of Mn and Fe during seed germination in water, whereas Zn was supplied from both endosperm and scutellum. Scutellum-stored Mn was not transferred to growing axis organs. During the period of intensive seedling growth mobilisation of micronutrients in grain depended on the rate of growth of axis organs, solubility of micronutrient compounds in grain tissues, and concentration of micronutrients in nutrient solution.