The use of hybrid carrots is a growing demand in the Brazilian market of seeds because they combine earliness and uniformity, as well as yield. We evaluated the effects of combining ability between carrot lineages for production components and tolerance to leaf blight. The crosses were carried out in a partial diallel 5x2, using five male-sterile lines of temperate and two male-fertile parents of tropical origin of the breeding program of Embrapa Hortaliças. The experiment was conducted at the experimental field of Embrapa Vegetables in the season 2011/12. The experimental designed was randomized blocks with three replications. The experimental plot consisted of a bed 1.0 m wide by 3.0 m in length. The ten hybrids and their male parents were evaluated for tolerance to leaf blight at 90 days after sowing. At 100 days plants were harvested and measured total and marketable roots yield, the ratio between them, weight, length and diameter of marketable roots. The analysis of variance was performed and the effects of general combining ability (GCA) and specific combining ability (SCA) were estimated. There were significant differences among hybrids for most traits. We detected predominant effects of GCA over SCA for most of yield components characters: weight of marketable roots (WMR, t ha-1) , total weight of roots (TWR, t ha-1), the relationship between WMR and TWR (PROP), mean weight of marketable roots (MWM), mean marketable root length (MRL) and mean marketable root diameter (MRD). SCA effects were significant for the tolerance to leaf blight. From these results we concluded that the male sterile lineages CNPH-11 and CNPH-72 and the male lineage CNPH-36 are the most promising for use in breeding programs aiming to produce hybrids.
Daucus carota; general combining ability; specific combining ability; hybrids
