- Ivan Simko: U.S. Department of Agriculture Agricultural Research Service U.S. Agricultural Research Station Crop Improvement and Protection Research Unit Salinas CA USA. ORCID
Baby leaf lettuce harvested approximately 30 days after planting is the primary component of spring mix salads, a popular type of packaged salads. Very little is known, however, about the content of vitamins, sugars, and pigments in young lettuce plants. Therefore, plants of 42 accessions harvested at baby leaf stage were analyzed for the contents of vitamin C, ß-carotene, anthocyanins, chlorophylls, glucose, fructose, and sucrose. Significant differences among accessions were found for content of all seven compounds plus sucrose sweetness equivalency () and average vitamin load (AVL). "Floricos" was highest in all sugars, and vitamin C; "Taiwan" was highest in ß-carotene and AVL, and "Annapolis" and "Darkland" were highest for anthocyanins and chlorophyll contents, respectively. The lowest content of glucose and sucrose was found in iceberg "Salinas," fructose in accession UC96US23, vitamin C in PI 257288, and β-carotene in "Solar." The lowest relative sweetness () was calculated for UC96US23, followed by "Salinas," while the lowest AVL was estimated for PI 257288. There were very strong, positive correlations among contents of the three sugars, and between β-carotene and vitamin C, and β-carotene and anthocyanins. Composition profiles of accessions presented in this study, together with identified associations between compounds, can be used by breeders, growers, and producers to select lettuces with desirable combinations of sugars, pigments, and vitamins. This information can help in development of new cultivars and breeding lines with desirable combination of traits, pleasing taste, and higher vitamin content.