Selection indices are, usually, linear combinations which allow simultaneous selection from several characters, being quite proper for recurrent selection schemes.Other non-linear-indices (multiplicative, sum of classification and distance to the ideotype) are also available, which do not depend on genetic or phenotypic trait estimates but might be used for genotype ranking. The main aim of this research work has been to establish the feasibility of using those non-linear indices in the end of a breeding program (selection of new cultivars). Data of 49 hybrids from Brazilian Early-Flowering Maize Trials (1996/97), carried out at nine locations, have ben utilized (adjusted means for the variables ear weiht, grain humidity per cent, days-to-flowering, plant height, ear height and percentage of broken and lodged plants). Stability and adaptability parameters have been calculated as well. Results have shown that the indices studied are not suitable for cultivar selection due to the following facts: a) they do not priorize the most important traits; b) do not allow the discarding of low value genotypes and c) cannot be used for multiple comparisons.
selection indices; cultivar selection; non-parametric indices; non-linear indices
