Genetic gain according to different selection criteria for agronomic characters in advanced tomato lines
Tomatoes are an important crop in Brazil. In advanced stages of breeding programs, the capacity to select or reject tomato lines becomes complex. We selected tomato lines comparing different selection strategies. We evaluated 115 advanced tomato lines from the Tomato Germplasm bank of the Federal University of Uberlândia. The following characteristics were evaluated: total chlorophyll content, foliar temperature, number of fruits, yield, distance between the first cluster and the soil, transverse and longitudinal fruit diameter, internode length and total soluble solids. Data was submitted to variance analysis, Scott-Knott's test of means, and selection gains estimates: direct and indirect selection, the classic Smith and Hazel index (SH), the Williams’ base index (W), the genotype-ideotype distance index (GID) and the Mulamba and Mock’s sum of ranks (MM). According to the Scott-Knott's test, the lines clustered in two groups for the variables number of fruits, yield, and distance between the first cluster and the soil. There was no consistency between the different selection indexes. Selecting 9% of the lines, total selection gains estimate for selection indexes were 12.57 (SH), and 38.57% (MM). With genetic gains more equally distributed among the characters, the MM index is suggested as the most appropriate for advanced stages of tomato breeding programs.