Morpho-physiological mechanisms of two different quinoa ecotypes to resist salt stress

Abstract

Background: Quinoa (Chenopodium quinoa Wild.) is a facultative halophyte, showing various mechanisms of salt resistance among different ecotypes cultivars. This study aimed to determine salt resistance limits for a Peruvian sea level ecotype “Hualhuas” and Bolivian salar ecotype “Real” quinoa cultivars and elucidate individual mechanisms conferring differences in salt resistance of these cultivars. The plants were grown in sandy soil and irrigated with various water salinity levels (0, 100, 200, 300, 400, and 500 mM NaCl) under greenhouse conditions. Results: At high salinity treatment, plant growth was reduced by 80% and 87% in Hualhuas and Real, respectively. Both cultivars were able to lower the osmotic potential of all organs due to substantial Na+ accumulation. However, Hualhuas plants exhibited distinctly lower Na+ contents and consequently higher K+/Na+ ratio compared to Real plants, suggesting a more efficient control mechanism on Na+ loading and better K+ retention in Hualhuas plants. Net CO2 assimilation rates (Anet) were reduced, being only 22.4% and 36.2% of the control values in Hualhaus and Real, respectively, at the highest salinity level. At full-strength salinity, Hualhuas plants showed lower stomatal conductance and transpiration rates, but higher photosynthetic water use efficiency, indicative of an efficient control mechanism over the whole gas-exchange machinery. Conclusion: These results reveal that Hualhuas is a promising candidate in terms of salt resistance and biomass production compared to Real.