“Heirloom” varieties as sources of variation for the improvement of fruit quality in greenhouse-grown tomatoes

Abstract

SummaryGreenhouse-grown tomatoes (Lycopersicon esculentum) often have poor internal organoleptic and nutritional qualities. “Heirloom” (traditional) varieties of tomato possess unique or superior fruit quality characteristics and may be useful for the development of new greenhouse tomato cultivars with improved internal quality. A collection of 55 North American “heirloom” varieties was evaluated for fruit colour, shape, weight, firmness (external quality traits) and total soluble solids (TSS) content, titratable acidity (TA), TSS:TA ratio, flavour intensity (FI; TSS TA) and ascorbic acid (AA) concentration (internal quality traits). The F1 hybrid ‘Daniela’ and pure line ‘NE-1’ were used as controls. A wide diversity was found among “heirlooms” for all traits studied, and several sources of variation (e.g., varieties ‘Moira’, ‘Paragon’, ‘White Queen’, ‘Black Prince’ and ‘Green Zebra’) useful for the improvement of fruit quality were identified. Brightness (L*), hue angle and chroma parameters facilitated the classification of varieties into colour groups (white, yellow, orange, red or black) and the identification of the varieties with better colour characteristics within each colour group. Although all “heirloom” varieties had lower firmness than the delayed ripening cv. ‘Daniela’, some of them (e.g., ‘Moira’ and ‘Paragon’) were very firm. Values obtained for TSS, TA, FI and AA demonstrated that many “heirloom” varieties had better organoleptic and nutritional qualities than modern varieties. As considerable variation was found for most traits, some of the materials studied represent sources of variation of great interest for tomato breeding.