AbstractThe climate of Mediterranean region will become drier and hotter, with increased problems of soil salinity. A possible alternative to minimize the effects of climate change is to introduce species with better tolerance to salt and drought stresses. One of the options is quinoa (Chenopodium quinoa Willd.), which was grown in field trials in several Mediterranean countries, to study the effects of drought and salinity on yield and other characters. Drought stress during the vegetative growth stage leads to deep root development, and without stress conditions for the rest of the growing season allowed the plant to be able to optimize its photosynthesis and carbon translocation. Stress during seed filling recorded the lowest yields. The influence of organic matter on yield was more important under deficit irrigation than under full irrigation. The interaction between relative water content and leaf water potential indicated that regulating cellular water deficit and volume is a powerful mechanism for conserving cellular hydration under drought. In all climatic conditions, drought and use of irrigation water with salinity up to 30 dS m−1 caused slightly reduced yield as compared to full irrigation with fresh water. Highest values of water conductivity resulted in higher seed weight, and as a consequence, an increase in fibre and total saponin content, and a small decrease in free phenolic compounds in quinoa seeds. The yield increase in quinoa accessions was less at the highest level of nitrogen application, that is, 200 mg kg−1 soil, compared with other levels of nitrogen application, that is, 50, 100 and 150 mg kg−1 soil.