Fruit component analysis of south Pacific coconut palm populations

The south Pacific region contains a large genetic resource for the genetic improvement of coconut palms (Cocos nucifera L.). A study of the diversity in the species was made during 1992/3 using fruit component analysis on a representative sample from 29 distinct south Pacific populations in order to characterise the germplasm present in the region. A large diversity in fruit morphology was found that ranged from populations exhibiting wild-type characters in central Pacific to populations displaying domesticated characteristics in Rennell Island, the Sikaiana Islands, the Marquesas Islands, and in Papua New Guinea. Many populations exhibited fruit characteristics intermediate between the two, which were thought to have arisen due to introgressive hybridisation between the wild and domesticated populations. Continuous variation in fruit morphology was found in these populations, and cluster analysis arbitrarily divided the continuum into discrete groups which were consistent with geographic affinities. Groups were defined in Melanesia, Western Polynesia and Eastern Polynesia. The continuum displayed clinal variation from populations with small fruit and low husk content in the west to large fruit and more husk in the east of the region. The wild and domesticated populations were found in disjunct pockets throughout the area, and did not form part of the clines. Most populations consisted of a wide range of fruit morphology, from individuals expressing wild-type characters to those with domestic-type characters. The occurrence of both wild and domesticated populations within the clinal variation indicates that further exploration should be made to determine the presence of other potentially useful populations. While this activity is proceeding, collection and conservation can proceed using the classification already defined.