Exogenous Myo-Inositol Promotes Sugar Beet Growth and Nutrient Uptake in Saline-Alkali Soil

Saline-alkali stress restricts crop yield by disrupting nutrient and water uptake, ionic balance, and oxidative homeostasis. Although myo-inositol enhances tolerance to abiotic stress, its role in sugar beet (Beta vulgaris L.) under saline-alkali conditions remains unclear. To investigate the effects of exogenous myo-inositol on sugar beet growth under saline-alkali soils, a pot experiment was conducted using six myo-inositol concentrations (0, 0.2, 0.4, 0.6, 0.8, and 1.0 g L^-1). Myo-inositol significantly influenced plant performance in a concentration-dependent manner. The 0.6 g L^-1 treatment produced the highest shoot and root fresh and dry weights, nearly doubling shoot biomass compared with the control. Shoot N and P contents increased markedly at 0.6 g L^-1, while their concentrations remained relatively stable, indicating biomass-driven nutrient accumulation. Myo-inositol reduced Na accumulation while maintaining stable K, Ca, and Mg concentrations, thereby improving ionic balance. Antioxidant capacity was enhanced, with superoxide dismutase and catalase activities significantly elevated. Root total length and surface area increased substantially, whereas specific root length and surface area decreased, suggesting improved root morphological development. Soil alkaline phosphatase activity was also stimulated at higher myo-inositol treatments. Overall, moderate myo-inositol application (with regression analysis indicating an optimum of approximately 0.56 g L^-1) improved sugar beet growth through enhanced nutrient acquisition, ionic balance, antioxidant capacity, and root development, offering practical insights for its use as a growth regulator in saline-alkali crop production.