Growth, physiological characteristics, and yield of quinoa after application of desulfurized gypsum in saline-alkali land

Soil salinization impedes agricultural development, and effective measures to improve productivity of such soils must be developed and implemented. In this study, we utilized Longchenli No. 4 as a test material to investigate the impact of three kinds of saline-alkaline soil (mild saline-alkali soil S₁: 3 g·kg⁻¹; Medium saline-alkali soil S₂: 5 g·kg⁻¹; and heavy saline-alkali soil S₃: 7 g·kg⁻¹) and four kinds of desulfurization gypsum application depth (FGD₀: not applied; FGD_0-10: 0－10 cm applied; FGD_0-20: 0－20 cm applied; and FGD_0-30: 0－30 cm applied) on agronomic traits, physiological parameters, and yield of quinoa under salt-alkali stress. A control group without saline-alkali stress and desulfurized gypsum application (S₀FGD₀) was included. The results showed that the low saline-alkali environment (S₁) promoted the growth of Chenopodium quinoa above ground and root and increased antioxidant enzyme activities, osmotic substances, root activity, and yield. Conversely, in high salinity and alkali environment (S₃), the agronomic and physiological parameters and final yield of quinoa decreased significantly (P < 0.05), consequently inhibiting the growth and development of quinoa. The application of desulphurized gypsum as an alkaline soil amendment 0－30 cm away from the soil surface significantly improved the agronomic parameters, antioxidant enzyme activity, root activity, and yield of quinoa and reduce the accumulation of osmotic substances (P < 0.05). This study provide scientific basis for the introduction of quinoa in saline-alkali land.