Genetic variation for bulb size, soluble solids content and pungency in the Spanish sweet onion variety Fuentes de Ebro. Response to selection for low pungency

Abstract

The cultivar ‘Fuentes de Ebro’ is a long-day onion grown in the northeast of Spain, which is characterized by its succulence and low pungency. However, to match the market demand the size, pungency, and storability need to be improved. We have evaluated these quality-related bulb traits in 15 grower’s open-pollinated lines of this cultivar. Phenotypic variation observed for bulb weight, size and soluble solids content was significantly affected by location, growing season and line, while pungency depended on line and plot location. We found higher levels of genetic variation for bulb size and pungency than for soluble solids content, and significant phenotypic correlations indicated that milder onion tend to show larger size and lower soluble solids content. After one cycle of selection, we have obtained progeny with significantly lower pungency levels, and therefore, we estimated a realized heritability of 0.67. As conclusion, it is feasible to obtain a sweet cultivar after some selection cycles in the ‘Fuentes de Ebro’ onion, although considering indirect consequences in size and soluble solids content