Comparative adaptive responses of quinoa cultivars grown hydroponically under saline-sodic stress

Pakistan has 22 million hectares (Mha) of cultivated land, of which 6.67 Mha are affected by salinity and sodicity, negatively impacting crop growth and quality. Quinoa, a facultative halophyte, was tested under hydroponic conditions to evaluate the effects of saline-sodic water on the growth, biomass, and ionic concentration of four quinoa cultivars (UAF-Q7, GLN-22, GLN-29, and GLN-33), and to assess their tolerance to salt stress. Five treatments were established: (i) control (no salt), and four saline-sodic irrigation waters with EC: SAR combinations of (ii) 10 dS m^- 1:20 (mmol L^- 1)^1/2, (iii) 10 dS m^- 1:40 (mmol L^- 1)^1/2, (iv) 20 dS m^- 1:20 (mmol L^- 1)^1/2, and (v) 20 dS m^- 1:40 (mmol L^- 1)^1/2. Seeds were germinated in a plant nursery, and uniform seedlings were transplanted to 25-L half-strength Hoagland's nutritional solution. To prevent osmotic shock, salt stress was gradually applied one week after transplantation.

Plant analysis showed that saline-sodic water negatively affected quinoa, particularly GLN-22. Among the tested cultivars, GLN-33 performed best at all EC: SAR levels, whereas GLN-33 and GLN-29 performed well at higher SAR levels. The GLN-22 cultivar showed sensitivity to all salt stress levels, as indicated by the increased accumulation of Na⁺ by 84% and 72% in the leaves and roots, respectively.

Based on the results, it was concluded that GLN-33 tolerated all stress levels up to EC 20 dSm^- 1 and SAR 40, with significantly better growth, lower Na⁺ accumulation (< 42% increase in leaves), and higher K⁺ retention compared to other cultivars. Thus, GLN-33 has the potential to grow efficiently in soils irrigated with saline water, owing to its effective defense system against salt stress.