COCONUT COCOS-NUCIFERA L SELECTION STRATEGY .2. IMPROVEMENT OF TALL X TALL HYBRIDS

The first part of this article gave a rundown of recent achievements in coconut breeding. The approaches described led to the implementation of the genetic improvement scheme used in Cote-d' Ivoire by the Institut de Recherches pour les Huiles et Oleagineux (IRHO). This scheme involves two main lines of work: improvement of Tall x Tall hybrids and improvement of Dwarf x Tall hybrids. This second part describes the method used for Tall x Tall hybrids. It consists in creating two populations around two very different ecotypes which have proved to perform well in hybridization. In Cote-d' Ivoire, the West African Tall (WAT) and the Rennell Tall (RLT) were chosen. In the first selection cycle, the different ecotypes are crossed with WAT and RLT with a view to splitting them into two groups: those ecotypes which combine well with WAT and those which combine well with RLT. Within-group crosses then make it possible to form two complementary populations. The following selection cycles improve these two populations with respect to each other using reciprocal recurrent selection on half-sib families. The merits of the method are discussed. It seems to be well adapted to the plant's biology and is based on prior breeding achievements. Using parents selected for their combining ability as testers makes it possible to take advantage of the basic genetic progress already achieved. The third part of this article will be given over to the improvement of Dwarf x Tall hybrids and to describing connections between the two selection channels: Tall x Tall and Dwarf x Tall. The possible integration of this method in an international research network will also be discussed.