Estimates of genetic gains in the carrot using different selection indices

Abstract

The carrot is one of the most important and preferred vegetables in Brazil due to its versatility and nutritional significance, especially as a source of vitamins. The selection of carrot genotypes should consider several agronomically important characteristics to allow more suitable and balanced gains. The aim of the present study was to estimate genetic gains in the carrot using different selection indices. Thirty-six carrot genotypes were evaluated in two experiments, the first conducted between 16 November 2017 and 1 March 2018, and the second between 5 March and 18 June 2018 in, Brasilia. In both trials. the experimental design was of randomised blocks with three replications. The plots were sown directly onto the seedbed, which had a total working area of 1.8 m2. The incidence of leaf blight was evaluated 78 to 98 days after sowing, at intervals of seven days, giving a total of four evaluations. The harvest was carried out at 105 days when the characteristics of the yield components were measured. An analysis of variance was applied, together with five selection indices: direct selection, classic, desired gain, weight- and parameter-free, and genotype-ideotype. There were differences between genotypes for most of the characteristics under evaluation. The genotype-ideotype index afforded the greatest gains for the characteristics being evaluated, with an economic weight equal to the coefficients of genetic variation; however other indices were also efficient and offered balanced gains, with the exception of the desired-gain index.