Estimates of general and specific combining ability for yield components in a partial sugarcane diallel cross
Marcelo de Almeida Silva;Marcos Guimarães de Andrade Landell; Paulo de Souza Gonçalves; José Antônio Bressiani and Mário Pércio Campana
The performance of 21 sugarcane progenies (Saccharum spp.) obtained in a diallel cross between three and seven varieties was evaluated from progeny tests conducted in Jaú Agronomy Experimental Station, Instituto Agronômico de Campinas, São Paulo State, Brazil. Measurements for average Brix, stool weight, stalk height, stalk diameter and stalk number were analyzed to obtain estimates of the relative magnitude of general (GCA) and specific combining ability (SCA) effects. Significant differences among GCA of the varieties were obtained for all characters, except stalk height, while significant differences among SCA effects were not expressed only for stalk height. An evaluation of variance components revealed that the variances of GCA for average Brix was almost the same of the component for SCA effects. A similar ratio for the two effects was obtained for stalk diameter. For average Brix, the ratio of GCA/SCA effects was bigger than the ratio observed for the other characters. This indicated that with the relatively bigger proportion of the genetic variance resulting from general effects, parental breeding value can be estimated from progeny of open-pollinated or polycross seed. The proportion of the genetic variance resulting from GCA effects of the other studied characters, the parental breeding value could be estimated from control-pollinated progeny tests.