Skip to main content

Official Journal of the Japan Wood Research Society

Journal of Wood Science Cover Image

Blackening of Diospyros genus xylem in connection with boron content


The amount of boron contained in the xylem of Japanese persimmon (Diospyros kaki Thunb.) and ebony (Diospyros ebenum Koen) was determined by inductively coupled plasma (ICP) emission spectrometry and a modified curcumin—acetic acid method. The boron content was compared between the heartwood and sapwood of ebony as well as between a blackened portion (“kurogaki”) and normal portion of Japanese persimmon. The kurogaki contained a higher level of boron than the normal portion of the same individual, although the boron content varied among individuals. Moreover, the boron content of the heartwood of ebony was much higher than that of the sapwood. These results suggest the participation of boron in the blackening of Japanese persimmon. Because both kurogaki and heartwood of ebony are durable to fungal attack, the blackening of Diospyros genus appears to be related to the formation of defensive substances in which boron seems to take part. The convenient curcumin—acetic acid method is an alternative to the ICP method with comparable accuracy.


  1. 1

    Yasue M, Ogiyama K, Ichinei J (1975) Extractive components in black portion of Japanese persimmon (in Japanese). Proceedings of the 25th Annual Meeting of the Japan Wood Research Society, p 180

  2. 2

    E Noda T Aoki K Minato (2002) ArticleTitlePhysical and chemical characteristics of the blackened portion of Japanese persimmon (Diospyros kaki) J Wood Sci 48 245–249 Occurrence Handle1:CAS:528:DC%2BD38Xls1ehtb4%3D Occurrence Handle10.1007/BF00771376

    CAS  Article  Google Scholar 

  3. 3

    H Yamada T Hattori (1986) ArticleTitleDetermination of total boron in soil by the curcumin—acetic acid method after extraction with 2-ethyl-1,3-hexanediol Soil Sci Plant Nutr 32 135–139 Occurrence Handle1:CAS:528:DyaL28XitVKjtbc%3D Occurrence Handle10.1080/00380768.1986.10557487

    CAS  Article  Google Scholar 

  4. 4

    T Fujihara J Takano M Kobayashi K Miwa (2002) ArticleTitleTransport and function of boron in organisms, especially in plants (in Japanese) Regulation of Plant Growth & Development 37 99–109 Occurrence Handle1:CAS:528:DC%2BD3sXhs1CisrY%3D Occurrence Handle10.1023/A:1020580427010

    CAS  Article  Google Scholar 

  5. 5

    HJM Bowen (1979) Environmental chemistry of the elements Academic London

    Google Scholar 

  6. 6

    BJ Rendle (1970) World timbers III. Asia and Australia and New Zealand University of Toronto Press London 16

    Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Kazuya Minato.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Minato, K., Morita, T. Blackening of Diospyros genus xylem in connection with boron content. J Wood Sci 51, 659–662 (2005).

Download citation

Key words

  • Boron
  • Curcumin method
  • Ebony
  • ICP analysis
  • Japanese persimmon