Optimizing Marketable Tuber Production in Potato (Solanum tuberosum L.) with Irrigation and Biostimulants Application

A field study was conducted to evaluate the combined effects of irrigation scheduling and amino acid-based biostimulants (AAB) on the growth and yield of potato (Solanum tuberosum L.) under Inceptisol conditions in the Middle Gangetic Plain, Uttar Pradesh, India, during two consecutive rabi seasons. The experiment followed a split-plot design with three irrigation regimes: I1 (three irrigations at three growth stages), I2 (four irrigations at four stages), and I3 (five irrigations at five stages), with 5 cm of water applied using a ridge-furrow system. Sub-plot treatments included four foliar biostimulant applications: control (A0), animal-based (A1), plant-based (A2), and a mixed amino acid formulation (A3), applied at key physiological stages. All biostimulants were applied in liquid form using a sprayer, diluted at a concentration of 250 mL per 100 L of water per hectare. Standard NPK fertilizer doses were applied, and soil properties were monitored before and after cultivation. Results indicated that both irrigation scheduling and AAB treatments significantly affected plant height, leaf area index (LAI), chlorophyll content, and marketable tuber yield across both years. Among the irrigation treatments, I2 resulted in the most favorable growth and yield parameters. The plant-based biostimulants (A2) consistently outperformed other AAB sources, significantly enhancing vegetative growth and tuber production. The I2A2 treatment combination yielded the highest values for plant height at 90 DAP (33.5 cm and 32.9 cm), LAI at 60 DAP (4.96 and 3.77), chlorophyll content at 30 DAP (43.77 and 44.62), and tuber yield per plant (255.00 g and 241.33 g) in the first and second field experiment, respectively. Significant interaction effects between irrigation levels and biostimulants types were observed for all measured parameters. These findings suggest that the strategic integration of a four-stage irrigation schedule with plant-derived AAB substantially improves marketable tuber yield by promoting vegetative growth and physiological performance in potato crops cultivated under Gangetic alluvial conditions.