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Propagation of Ornamental Plants
16(4): 137-145, 2016
SEED CHARACTERIZATION FOR PROPAGATION AND CONSERVATION OF OXERA PULCHELLA SUBSP. GRANDIFLORA (DUBARD) DE KOK, A NEW CALEDONIAN ORNAMENTAL ENDEMIC
Charly Zongo1, Margaux Sabourin2, Laurent Démaret1, Gildas Gâteblé1, Bruno Fogliani1, and Philippe Marmey2*
1 Neocaledonian Agronomic Institute (IAC), BP 73, 98890 Païta, New Caledonia 2 UMR DIADE, French National Research Institute for Sustainable Development (IRD), BPA5, 101 Promenade Roger Laroque, 98848 Nouméa Cedex, New Caledonia, *Fax: + (33) 4-67-41-62-22, *E-mail: philippe.marmey@ird.fr
The Royal Creeper, Oxera pulchella subsp. grandiflora (Dubard) de Kok (Lamiaceae) is a New Caledonian threatened endemic taxon with high ornamental potential. Propagation by cuttings has till now been the main propagation method for ornamental uses. A characterization of the seed biology is required in order to promote a better development of O. pulchella subsp. grandiflora ornamental potential, through maintaining its genetic diversity and its conservation. A seed analysis was conducted to define seed structure, germination conditions, dormancy, and desiccation tolerance. Seeds were shown to be of exalbuminous type with a permeable endocarp. Seeds displayed a non-deep physiological dormancy. When desiccated by equilibration in nine atmospheres with controlled relative humidity, seeds desiccated to lower water content (2.8 ± 0.5% of fresh weight) displayed a germination rate of 63 ± 13% compared to non-desiccated control, indicating that Oxera pulchella subsp. grandiflora seeds were desiccation-tolerant. Protocols combining seed desiccation and low temperatures storage revealed that seeds desiccated in an atmosphere with a relative humidity of 45% and conserved at 4°C were viable after one-year period storage, with a germination rate of 50%. Our study shows that a characterization of physiological traits of seeds, such as germination, dormancy and desiccation tolerance, may lead to favoring the seed as a means of propagation for ornamental uses and conservation.
Key words: Desiccation, conservation, royal creeper, South Pacific
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