Tools for breeding ‘calçots’ (Allium cepa L.), an expanding crop

Abstract

‘Calçots’, the floral stems of second-year onion resprouts of the ‘Ceba Blanca Tardana de Lleida’ landrace, have a growing market. Different constraints have prevented the inclusion of sensory attributes in ‘calçot’ breeding programs. Thus, we aimed to: (i) elaborate a sensory ideotype representing consumers’ preferences for ‘calçots’, (ii) design an easy protocol for preparing samples and training a sensory panel to evaluate them, and (iii) describe the sensory attributes of ‘calçots’ derived from the main Spanish landraces of onion to point out possible strategies for breeding for sensory quality. A selected group of consumers determined that the sensory ideotype of ‘calçots’ should have high sweetness, low fiber perception, and no off flavors. Samples of 50 ‘calçots’ from a single accession, roasted in the oven at 270°C for 18 min, stripped of their two external leaves, cut off at a height of 20 cm, and puréed, proved adequate for sensory panel evaluation even after being frozen and defrosted. A panel was trained until it was good at distinguishing between accessions (when neither the panelist effect nor the interaction panelist × accession was significant). This trained panel found many significant differences in sensory traits among the ‘calçots’ from Spanish landraces of onion. Although, none of these landraces was as close to the ideotype as the ‘Ceba Blanca Tardana de Lleida’ landrace traditionally used for ‘calçots’, crosses with some of these varieties would probably lead to heterotic base populations for breeding. The genotypic correlations found suggested that agromorphologic and sensory advances are compatible, so the information given should promote the inclusion of sensory quality as a new breeding objective.

Key words: Ideotype, ‘Calçot’, onion, sensory attributes, genetic variability, sample preparation, spanish landraces, panel training.