Heat Stress Lowers Yields, Alters Nutrient Uptake And Changes Seed Quality In Quinoa Grown Under Mediterranean Field Conditions

The global expansion of quinoa (Chenopodium quinoa Willd.) cultivation has been related to the nutritional properties of its seeds and the ability of this crop to cope with stress. However, research works evaluating the agronomic impact of quinoa cultivation out of the Andean region are still limited, especially under Mediterranean field conditions. In this work, the agronomic performance, seed composition and nutrient uptake (NU) of five quinoa varieties were analysed in two consecutive years (2017-2018) under field conditions in Southwestern Europe. High temperatures were recorded during 2017 growing season, resulting in significantly lower yields (1.6 t/ha) compared to 2018 (2.5 t/ha). High-temperature stress coincided with flowering stage in those medium-to-long cycle varieties and was well correlated with detrimental effects on the vegetative stage of short and medium cycle varieties. Seed composition and mineral content of quinoa varied among varieties subjected to heat stress, which could be due to differences in the stress response. Protein and fibre contents were higher under high temperatures, while fats and carbohydrates contents decreased. Nutrient uptake, utilisation and partitioning were reduced under heat stress, probably due to heat-protection mechanisms and associated biochemical changes. Early maturing varieties showed better adaptation, especially Marisma, which achieved the highest yield in both years (3.0 t/ha, on average). Overall, the results here presented support to the potential of quinoa cultivation in Europe highlighting the necessity to further explore varieties better adapted to elevated temperatures, a common stress affecting the Mediterranean area.