Synergistic Role of Calcium and Cobalt in Enhancing Sugar Beet Yields under Water Deficit Conditions

Two field experiments were conducted during the 2021-2022 and 2022-2023 seasons at Mallawi Research Station, Minya, Egypt, to evaluate the effect of foliar applications of calcium chloride and cobalt chloride on sugar beet yields under different irrigation regimes. A split-plot design with three replicates was used, where irrigation regimes (full irrigation, one omitted irrigation, and two omitted irrigations) were assigned to the main plots, while subplots were foliarly applied with calcium chloride (0, 4, and 8 kg/fed) and cobalt chloride (0, 10, 20, and 30 ppm). Growth and yield components, including root length, diameter, weight, root-to-shoot ratio, and root and sugar yields, were evaluated.Results showed that moderate water stress (after a single irrigation) with calcium and cobalt supplementation significantly improved root growth and sugar yield compared to full irrigation alone. Calcium chloride improved root elongation, root thickness, and root/shoot ratio, with the highest results recorded at 8 kg/acre. Cobalt chloride at 20 ppm improved root weight and sugar yield, while higher concentrations reduced performance. The best combination was moderate irrigation with 8 kg of calcium chloride and 20 ppm cobalt, which improved sugar yield (6.70 t/fed.) and root performance. Severe stress significantly reduced yield, even with the addition of nutrient supplements.Overall, the results highlight that the integrated application of calcium and cobalt under moderate water stress can enhance sugar beet productivity while reducing irrigation requirements, providing a practical strategy for water-efficient agriculture in arid regions.