Resumo

DE SOUSA-VIEIRA, Orlando  e  MILLIGAN, Scott B. Effect of intrarow plant spacing on the effectiveness of family selection in sugarcane: Selection indices. INCI [online]. 2009, vol.34, n.12, pp.893-896. ISSN 0378-1844.

Cross prediction trials or progeny tests for family selection are commonly employed at the beginning of each breeding cycle in clonally propagated crops such as sugarcane (Saccharum spp. Hybrid). When selecting sugarcane families, the factors affecting variability between and within those families should be considered. This research examined the influence of family and intra-row plant spacing on the efficiency of the index selection procedure as a method of simultaneous improvement of a population for multiple traits at the first selection stage of the Louisiana Sugarcane Variety Development Program (LSVDP). Therefore, the main objective of this study was to develop a selection index for selecting sugarcane families within the LSVDP. Expected genetic advance values for plant weight were greater in the wide-spaced indices than in the narrow-spaced ones. Irrespective of plant spacing, selection indices revealed that an increase in efficiency was observed over direct selection for plant weight when all four plant weight contributing traits were included along with plant weight. The efficiency in selection tended to decrease when indices were based on fewer traits. Nevertheless, a few of the indices that included two traits had relative efficiencies comparable to the best indices and the majority certainly was as effective as direct selection for plant weight.

Palavras-chave : Clonal Propagation; Family Selection; Index Selection; Plant Breeding; Saccharum spp.