Studies on the Epidermic Browning of Lotus Rhizome

The brown colored lotus rhizomes are usually produced by common cultural practices. When the brown substances were formed high concentration on the rhizomes, their marketabilities were reduced extremely because of undesirable color.The browning substances were determined and their seasonal changes were also determined in this study.1. The amount of brown substances increased continuously until late-Sept., then decreased steadily. Such seasonal change suggests that the brown formation and dissolving is caused by oxidation and reduction which is closely associated with the lotus growth and the soil conditions.2. The smaller quantities of brown substances were situated in the first node of rhizome, but were larger in the later nodes, while the brown formation in each node itself was observed largely in the portion of growth direction of that node.3. The analytical results of brown substances by fluorescent X-ray showed that Fe is a dominant and was followed by the small Mn. Other metalic elements such as Zn, Ni and Cu, though detected in a slight amount, were not at all clear why existed in this substances. It was supposed by some quantitative analysis that the brown substances exist principally in oxidized or similar formulas.4. Since there is a strong relationship between Fe contents and L-values (color) in rhizome, the approximate contents of Fe or Mn could be obtained only by measurement of L-value with relation of equality linear function.5. The amount of brown substances between experimental plot A and B differed considerably. The compost application (plot-B) reduced the accumulation of brown substances. Therefore, it was supposed that the compost plays as important role in diminishing functions of brown phenomenon.