Abstract <p>The influence of soil-water regimes and plant-protection systems on biometric indicators of potato plants and productivity of commercial tubers have been studied. The work was carried out in 2021–2023 in Volgograd oblast. The scheme of the field experiment involved the variants with the moisture regime in the 0–0.4-m soil layer (factor A) not lower than 70% of minimum moisture-holding capacity (MMC) (A₁) or not lower than 80% MMC (A₂); the potato plant-protection system (factor B) included biological protection system (B₁), integrated protection system (B₂), or chemical protection system (B₃). The experiment was carried out on the planting of potatoes (Gulliver variety) on light chestnut heavy loamy soil. The longest potato-growing season was detected for the background (moisture regime in the 0–0.4-m soil layer not lower than 80% MMC), which, depending on the protection system, varied from 87 to 102 days (in 2021 and 2023, respectively). The maintaining of the preirrigation moisture threshold in the soil layer of 0–0.4 m of at least 70% MMC shortened the growing season of potato plants: it varied from 85 to 98 days for 2021 and 2023, respectively. The highest yield of commercial tubers during the experiment was obtained in the variant with the application of biological protective agents and the soil-water regime at the level of 80% MMC (at a depth of 0–0.4 m). On average, over 3 years of studies, the value of this indicator was 26.9 t/ha, which is 5.1 t/ha more than for the variant with the treatment with chemical plant-protection products.</p>