Effect of irrigation salinity on yield and quality of seeds in different quinoa genotypes

Subtropical arid regions face challenges such as high temperatures, poor soil fertility, and saline soils and water. Quinoa (Chenopodium quinoa Willd.) is well-suited for these areas, particularly in the Middle East and North Africa, where it is cultivated with saline irrigation. This study evaluated the seed yield and quality of eleven quinoa genotypes under two salinity levels (1 and 15 dSm−1) in sandy soils at the International Center for Biosaline Agriculture (Dubai, UAE). Key traits measured included seed yield (SY), biomass, plant height (PH), days to flowering (DF) and maturity (DM), thousand seed weight (TSW), and carbon (δ13C) and nitrogen (δ15N) isotope composition, alongside nitrogen, mineral, and essential amino acid content. Salinity reduced PH and biomass by 20 %, TSW by 6 %, and SY by 30 %, although the ICBA-Q5 variety showed positive effects on SY and biomass under saline conditions. Salinity increased δ13C and δ15N and had a minor impact on minerals, with moderate increases in zinc and sulfur. Amino acids showed slight reductions in isoleucine, leucine, and threonine. Genotypic effects were more significant than salinity, with Ames-13757 performing best for SY and biomass under both control and saline conditions, and NSL-106399 displaying the highest amino acid content under salinity. δ13C and DF negatively correlated with SY, while δ15N was linked negatively to some minerals and amino acids. The study found a low trade-off between seed yield and quality under salinity. Quinoa is highly adaptable to saline irrigation in the UAE, and genotype selection is key for optimizing yield and quality.