Botany and Genetics of New Caledonian Wild Taro , Colocasia esculenta 1

Taro, Colocasia esculenta (L.) Schott, is considered to be an introduced crop in New Caledonia and has been cultivated since its introduction by Melanesian farmers. Wild germplasm exists on the main (continental) island and is represented by three easily distinguished morphotypes: a morphotype with purple leaves, another with green leaves, and a third with green leaves and a purple vein junction on the lamina. All three morphotypes are diploids (2n = 2x = 28) and have well-established wild populations in many valleys and gulches of the main island. The morphotype with purple leaves has all typical traits of a wild genotype (inedible corms; long, thin stolons); the other two produce edible corms. The purple and the green morphotypes flower and produce fertile pollen. The spathes of the green morphotype can be more than 40 cm long and the spadix is characterized by an extremely long appendix atypical for Pacific taros. Isozyme analysis conducted using four enzyme systems (EST, PGM, PGI, SkDH) indicated that New Caledonian wild taros differ from most widely grown local cultivars and Pacific cultivated and wild genotypes. Evidence presented in this study suggests that C. esculenta is an endemic species to New Caledonia. Cultivars were probably introduced as clones from what is now Vanuatu by early Melanesian migrants and were not domesticated locally from existing wild forms, which appear to be genetically distant from other Melanesian wild taros. TARO, Colocasia esculenta (L.) Schott, is a ferred to different places, and many wild vegetatively propagated root crop species of populations have been destroyed by intense the monocotyledonous family Araceae and is agricultural practices. grown in almost all tropical regions of the The origin of wild germplasm in some world. It is generally believed that this species Pacific countries (Australia, Papua New originated in Indo-Malaya although there Guinea, the Solomons, and Vanuatu) is also is insufficient evidence. Taro's center(s) of controversial. If taro was brought to these origin, spread, and domestication have been countries it was probably brought in a cultistudied by several authors (Spier 1951, Yen vated and not in a wild form. It is unlikely and Wheeler 1968, P1ucknett 1984, Jones and that migrating people collected and disMeehan 1989, Matthews 1990, Lebot and tributed wild genotypes that had inedible Aradhya 1991, Lebot 1992). It is possible corms with very high concentration of oxthat the center will never be found because alates. Wild germplasm has not been studied much-gerretic~evidetIt~"naTalreaQy-oeenlos[----thorougl11y.-Breeoersnave -avoiaecrwil<rge: Many cultivars have disappeared or transnotypes because of their many negative characteristics. In the future, however, wild genotypes may become an important source of genes for the improvement of resistance and/ or tolerance to pests and diseases, adaptability to extreme drought or paddy environment, earliness, long growth period, and other characteristics.