Chikako Okumura

Effects of Fe fertilizer eluate on the growth of Sargassum horneri at the germling and immature stages

To aid in the restoration of coastal barren ground areas, it is important to clarify the effects of chelated iron on the growth of seaweed. In particular, for the further development of practical methods to promote seaweed growth, Fe-binding organic ligands, such as humic substances (HSs) composed of humus materials, rather than Fe-binding inorganic ligands, such as ethylenediaminetetraacetic acid (EDTA), should be investigated. In this study, the effects of an Fe fertilizer, made from HSs and steelmaking slag, on the growth of the brown alga Sargassum horneri at the germling and immature stages were examined. The addition of the Fe fertilizer eluate containing Fe organic ligand complexes clearly promoted the growth of S. horneri at the germling and immature stages. It was also clear that the effect of Fe concentration in the Fe fertilizer eluate on the growth rate was almost the same as that of Fe–EDTA. Moreover, the addition of the Fe fertilizer eluate had a great effect on the brown color of S. horneri thalli and promoted the increased content of photosynthetic pigments, such as chlorophyll a. Based on these experimental results, the application of the Fe fertilizer containing Fe organic ligand complexes is expected to become an effective method for the restoration of the barren ground phenomenon in Fe-deficient coastal areas.

Erratum to: Contrasting effects of blue and red LED irradiations on the growth of Sargassum horneri during the germling and immature stages

The brown seaweed Sargassum horneri (Sargassaceae) is important for marine environment conservation. It could be used for a food material, medical applications, and future biofuel production. We compared the growth of S. horneri cultures under single wavelength blue and red light during the germling and immature stages. The growth rate based on the thallus area of S. horneri during the germling stage was faster under blue LED light than under red LED light. Furthermore, based on the wet weight of S. horneri, during the immature stage, blue LED light resulted in a faster growth rate than red LED light. Moreover, during the immature stage, compared with red LED light, blue LED light tended to increase the content of photosynthetic pigments. We conclude that use of blue LED light in indoor tanks during the germling and immature stages will improve the efficiency of S. horneri culture.