Abstract Potato yield is highly dependent on phosphorus (P) availability. Although high rates of P fertilizers are commonly applied to potatoes even in high P test soils, the efficiency of these practices is questionable. Foliar P fertilization, particularly during the tuber bulking stage, has emerged as a potential complementary strategy. This study aimed to evaluate whether adjusting the conventional P application rate at planting and applying in-season foliar P could optimize potato production. A field experiment was conducted on tropical Oxisols with high P-resin concentrations (74–123 mg P dm −3 ) in three site-years in southeastern Brazil. Treatments included five soil P rates at planting (0, 22, 44, 88, and 177 kg P ha −1 ) combined or not with three foliar P applications (1.3 kg P ha −1 each) during tuber bulking. Even without soil- or foliar-applied P, potatoes grown in these soils exhibited adequate P nutrition and high tuber yields (43.1–54.8 Mg ha −1 ); however, minimum soil P rates still enhanced tuber initiation and yield. Foliar P application increased leaf P concentration, uptake, and recovery efficiency across all planting P rates but did not improve tuber yield or quality. Increasing planting P rates produced modest yield gains (6.5%), with estimated optima at 33 or 53 kg P ha −1 depending on the regression model. Potatoes can still respond to P fertilization even in soils testing high in P, but substantially lower P rates than those traditionally used in commercial production are sufficient to achieve high yields. Foliar P application did not improve tuber yield or quality. Graphical Abstract

Abstract Among the most cultivated crops worldwide, potato ( Solanum tuberosum) faces significant threats from water scarcity, owing to its shallow root system and high irrigation requirement. Water deficit disturbs homeostasis and critical physiological mechanisms, including photosynthesis, carbohydrate translocation, and starch metabolism in tuberous plants. It reduces CO₂ assimilation, modulates the expression of key enzymes involved in starch synthesis, such as ADP-glucose pyrophosphorylase and starch synthases, and alters the amylose–amylopectin ratio, consequently affecting their rheological properties. Additionally, drought triggers antioxidant and metabolic responses in plants, including the accumulation of secondary metabolites and the regulation of stress tolerance-related genes. Transcriptomic analyses have revealed water-deficit responsive genes, such as StMAPK11 , StCDPK13 , and StERF94 , which contribute to stress adaptation. This review also explores mitigation strategies and genetic improvement approaches, including the application of biostimulants (chitosan, uniconazole), ZnO and SiO₂ nanoparticles, and the selection of more drought-tolerant genotypes. Recent advances in biotechnology, including gene editing and omics technologies, have contributed to the development of stress-resilient potato varieties.