Root anatomy and spatial pattern of radial oxygen loss of eight true mangrove species

N. Pi, N. F.Y. Tam*, Y. Wu, M. H. Wong

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

133 Citations (Scopus)

Abstract

The root anatomical features of eight mangrove species in Hong Kong were similar, with large aerenchymal lacunae in the cortex for efficient internal oxygen transfer and an outer barrier consisting of an epidermis and hypodermis to prevent oxygen loss. The spatial pattern of radial oxygen loss (ROL) was also comparable, with more oxygen lost from the tip than that from the basal and mature zones. However, the aerenchyma in the cortex, the barrier and the extent of ROL varied along the root and these variations were species-specific. The whole root of Avicennia marina (Forsk.) Vierh., Acanthus ilicifolius L., Aegiceras corniculatum (Linn.) Blanco, Kandelia obovata Sheue, Liu & Yong (previously known as Kandelia candel (L.) Druce) and Heriteria littoralis Dryand. ex W. Ait. had schizogenous aerenchyma, while the aerenchyma of Lumnitzera racemosa Willd. and Bruguiera gymnorrhiza (L.) Poir changed from schizogenous in the root tip to lysigenous in the other parts of the root. Excoecaria agallocha L. displayed the opposite pattern, from lysigenous in the root tip to schizogenous further up. Among the eight species, the roots of A. marina and A. ilicifolius had the largest areas of aerenchyma air spaces, but they also had the weakest barrier. On the other hand, H. littoralis had the least longitudinal oxygen transfer because of its smaller area of aerenchyma air spaces in its root. The tolerance of mangrove species to waterlogged soil followed the order of A. marina (most foreshore species) > A. ilicifolius > K. obovata > A. corniculatum > B. gymnorrhiza > E. agallocha > L. racemosa > H. littoralis (most landward species), which is related to their anatomical features of root cortex, epidermis and hypodermis.

Original languageEnglish
Pages (from-to)222-230
Number of pages9
JournalAquatic Botany
Volume90
Issue number3
DOIs
Publication statusPublished - Apr 2009

Scopus Subject Areas

  • Aquatic Science
  • Plant Science

User-Defined Keywords

  • Aerenchyma
  • Barrier
  • Epidermis
  • Hypodermis
  • Mangroves
  • ROL

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