Coconut (Cocos nucifera L.) genetic improvement in Vanuatu: Overview of research achievements from 1962 to 2002.Part 2: Improvement of the Vanuatu Tall by hybridization

摘要

From 1962 to 2002,at the Saraoutou research station on the island of Santo in Vanuatu,a hybrid creation programme was implemented to improve the productive potential of coconut cultivars.The first stage was to create a collection by introducing around thirty exotic varieties.All those varieties and most of the 60 hybrids created proved to be susceptible to coconut foliar decay,a viral disease transmitted by Myndus taffini and endemic in Vanuatu.Only the Vanuatu Tall populations and two hybrids (Vanuatu Red Dwarf x Vanuatu Tall and Vanuatu Tall x Rennell Island Tall) displayed tolerance enabling their distribution to farmers.The author indicates the origin of the parents and the production characteristics of these two hybrids.The Vanuatu Red Dwarf x Vanuatu Tall hybrid expresses good hybrid vigour with a production potential ranging from 2.5 to 3.4 tons per hectare per year.However,it does have several defects:slow germination and a highly irregular final germinated nut rate,susceptibility to cyclones when young,premature nut fall sometimes seen on young palms,and a mediocre copra content (between 135 and 160 g).The Vanuatu Tall x Rennell Island Tall hybrid stands out through its early start to bearing (4 years),its vigour and its good adaptation to cyclones.The copra content of its nuts (between 210 and 245 g) is better than that of the Vanuatu Tall,making copra preparation easier.Its production ranges from 2.5 to 3 tons per hectare per year,which is around 30% better than the improved Vanuatu Tall (Elite Vanuatu Tall).However,dissemination of this hybrid,which can only be produced in centralized seed gardens,is limited byAhe'cost of production and of transport throughout the archipelago.Only large-scale Elite Vanuatu Tall production in decentralized seed gardens would enable a significant improvement in coconut productivity in Vanuatu.