This paper presents the findings of a three-year pot experiment investigating the protective effects of pre-sowing seed treatment with solutions of selenium, vanadium, tungsten, and iodine salts on the biometric characteristics, yield, and grain quality of buckwheat. During the early budding stage, a subset of plants was subjected to an artificially induced water deficit. The study was conducted on two soils of the same subtype but with differing levels of available phosphorus. To ensure adequate mineral nutrition, all pots were amended with N (150 mg/kg) and K 2 O (100 mg/kg of soil). Analysis of the yield components revealed that the salts used had no significant effect on the number of inflorescences or the thousand-kernel weight. The protective properties of these ultramicroelements were most pronounced under drought conditions combined with low phosphorus availability: the application of sodium selenite reduced grain yield losses by 32%, ammonium vanadate by 20%, ammonium tungstate by 14%, and ammonium iodide by 25%. In the absence of seed treatment, yield was strongly influenced by an increased content of soil available phosphorus; under optimal moisture, buckwheat produced 40% more grain, and after drought, 70% more compared to plants grown on low-phosphorus soil. No significant changes in the chemical composition of the grain were identified across the various growing conditions (application of ultramicroelement salts, varying soil available phosphorus levels, or water availability).