MELHORAMENTO POPULACIONAL DE ARROZ DE TERRAS ALTAS E SELEÇÃO DE LINHAGENS PROMISSORAS PARA AS CONDIÇÕES DE SAVANA DA COLÔMBIA

Since 1996, the collaborative project between CIRAD (Agricultural Research Centre for International Development) and CIAT (Centro Internacional de Agricultura Tropical) has gradually phased out intra-specific tropical japonica conventional crossbreeding activities and concentrated on rice genetic base broadening. The development and enhancement by recurrent selection of upland rice composite populations are the new breeding strategies. Using a recessive male-sterile gene (ms), the development of rice population was made easier. In Colombia, upland basic composite populations were enhanced using two recurrent selection-breeding methods: mass recurrent selection and S2 progenies evaluation. At each enhancement cycle, fertile plants are selected for the development of segregating lines and progeny selection using the conventional pedigree method. The most advanced lines are evaluated in yield trials by the project and in collaboration with the Colombian research organization – Corpoica Regional 8, in Villavicencio, Colombia. Promising lines having good adaptation to acid soils were identified. One promising line, extracted from the first cycle of recurrent selection of the composite population PCT-4, shows a higher yield potential with the same earliness of the best commercial check (Linea 30), developed by conventional crossbreeding. KEY-WORDS: Upland rice; recurrent selection; composite population; promising line.