Genetic gains for root characters in carrot populations in conventional and organic production systems

The objective of this work was to evaluate the genetic gain with the selection of root characters of carrot populations cultivated in organic and conventional production systems. The experiments were carried out at Embrapa Hortaliças, Brasília, Brazil. Two carrot populations derived from Brasília cultivar and with common origin until 2002, were separate in two populations and evaluated for eight generations during 2000 to 2007. In 2008, seed samples of the population in each cycle of selection were sowed in the field in both organic and conventional production systems, in a randomized blocks design with four replications of nine treatments and plots of 1 m². After 90 days of sowing, 20 roots per plot were harvested for the evaluation of the length, xylem and phloem diameter, green shoulder length, fresh mass, presence of halo, tip and shoulder format, and the color parameters of xylem and phloem. Variance analysis was carried out to determine the interaction between treatments and production systems, grouping of means among treatments, and the real gain with the selection was estimated. In the last eight years of selection, a significant gain was not observed on the studied characters in the two populations. So we concluded that those traits are already quite developed and stabilized in both populations. The selection doesn't need to be accomplished in both areas of organic and conventional cultivation, making possible the decrease of financial and labor resources utilized in the breeding.

Daucus carota; interaction genotype x environment; genetic progress