Exploiting the relationship between the nutritional properties of seeds and the genetic background, constitutes an essential analysis which contributes to broadening our knowledge regarding the control of the nutritional quality of seeds or any other edible plant structure. This constitutes an important aspect when aiming at improving the nutritional characteristics properties of crops, including those of Chenopodium quinoa Willd (quinoa) which is intended to be one of the main nutrient sources ensuring food security worldwide. Changes in the nutritional properties of quinoa seeds due to the influence exerted by the environment, the genotype, or their interaction, have been already described in previous works, but there is an important limitation in the analyses carried out, including the outcomes that can be translated into agronomical practices by which quality can be improved selecting the most adequate genotype. In the present study, several seed nutritional-related parameters from fifteen quinoa cultivars grown in a particular environmental context were analyzed aiming at targeting compounds that can be determinants of seed quality. Important agronomical and nutritional differences were found among cultivars such as distinct mineral or protein contents and seed viability. More importantly, our analyses revealed key correlations between seed quality-related traits in some cultivars, including those that relate yield and antioxidants or the germination rate. These results highlight the importance of considering the genotypic variation in quinoa when selecting improved quinoa varieties with the best nutritional characteristics for new cultivation environments.