| Summary: | Salinity combined with a deficiency of potassium (K) and zinc (Zn) negatively affect sugar beet yield and quality. A two-year (2017/18–2018/19) field trial was undertaken to investigate the mediating role of soil-applied K [120 (K<sub>120</sub>) and 180 (K<sub>180</sub>) kg ha<sup>−1</sup>] and foliar-applied Zn [0 (Zn<sub>0</sub>), 150 (Zn<sub>150</sub>), and 300 (Zn<sub>300</sub>) ppm] in alleviating salt-stress (8.60 dS m<sup>−1</sup>) based on sugar beet morpho-physiological responses, sugar yield and quality, and K-use efficiency in the BTS 301 and Kawemira cultivars. Application of K<sub>180</sub> × Zn<sub>300</sub> was more effective and resulted in 23.39 and 37.78% higher root yield (RY) and pure sugar yield (PSY), respectively, compared to control (K<sub>120</sub> × Zn<sub>0</sub>). It also enhanced sucrose, pure sugar (PS), and purity but decreased impurities (α-amino N, K, and Na), alkalinity index, and sugar loss. However, the K<sub>120</sub> × Zn<sub>300</sub> recorded higher K-use efficiency. PSY correlated positively (<i>r</i> = 0.776 **, 0.629 **, 0.602 **, 0.549 **, and 0.513 **) with RY, root fresh weight (RFW), top yield, PS, and root diameter, respectively. The stepwise and path-coefficient analysis demonstrated that RY, PS, and RFW were the most influential PSY-affected attributes. Integration of K<sub>180</sub> + Zn<sub>300</sub> can correct K and Zn deficiencies in the soil and mitigate salt-stress effects via improving sugar beet growth, yield and quality, and K-use efficiency.
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