Methods to promote germination of two Cunoniaceae species, Cunonia macrophylla and Geissois pruinosa, from New Caledonia

The response of germination of seeds from two New Caledonian Cunoniaceae, Geissois pruinosa Brongniart and Gris and Cunonia macrophylla Brongniart and Gris (which have interesting biological and horticultural properties) to temperature and soaking level was established. It also permitted definition of the temperature range for germination and the thermal optimum. The seeds of these two species possess different germination profiles. Soaking appears to be more important for C. macrophylla seeds than for G. pruinosa seeds. In order to optimise germination factors, reduce latent time and increase the germination capacity, seeds were exposed to different types of pre-treatment: cold; sulphuric acid; hot water and mechanical scarification. The latter two seem to be the most effective and economic for both species. The other forms of treatment appear ineffective and even harmful.