Iron Requirement for Chlorella

Abstract

There is a lack of fundamental data on the Fe requirement of plants due to failure to consider amount of Fe actually present in a soluble form. This objection has been overcome by adsorbing practically the last traces of Fe at alkaline reactions and by using sufficient Na citrate to keep the Fe subsequently added in solution indefinitely. A high minimum Fe concentration was found for growth of Chlorella. This concentration was higher in those series which had a higher Na citrate content, due possibly to the fact that Fe is active in growth only in the ionized form and that increasing the amount of citrate ion decreases the ionization of the Fe citrate present. Therefore, while in certain cases a larger total amount of Fe may be present, little or no growth occurs because of a low concentration of the ferric ion.