Foliar Application of Commercial Amino Acids Biostimulants on Nutrient Uptake and Quality of Potato Tuber

The field experiments were conducted in the middle Gangetic plain sub-tropical region of India. The objective of the research was to assess the nutrient uptake and quality of potato tubers under various irrigation schedules and commercial amino acid biostimulant (AAB) treatments. The field trial used a split-plot design incorporating three irrigation schedules at key crop growth stages: three irrigation stages (I₁; 3 irrigations), four stages (I₂; 4 irrigations), and five stages (I₃; 5 irrigations), along with four different sources of AAB: A₀ (control), A₁ (Siapton 10L), A₂ (Amino acid liquid), and A₃ (Amino Plus), combined with the recommended dose of fertilizers. The quality and nutrient uptake of the tubers were significantly enhanced by spraying all the sources of AAB. The plant-based biostimulant (A₂) led to the greatest increase in total soluble solids (TSS, 18.12 to 28.20%), starch (21.36 to 23.93%), and protein content (2.11 to 2.76%), followed by the mixture amino acid biostimulants (A₃), and the lowest response was observed with the animal-based biostimulants (A₁). The maximum nutrient uptake was observed with the A₂ treatment, with nitrogen uptake ranging from 65.74 to 152.26 kg ha^− 1, 120.12 to 163.23 kg ha^− 1, and 74.90 to 79.69 kg ha^− 1 at 30, 60, and 90 DAS, respectively, followed by A₃ and A₁. Maximum phosphorus uptake by A₂ ranged from 32.54 to 107.50 kg ha^− 1, 47.73 to 70.57 kg ha^− 1, and 56.78 to 47.73 kg ha^− 1 at 30, 60, and 90 DAS, respectively, followed by A₃ and A₁. The same trend was observed for potassium uptake. Regarding the irrigation schedule, all treatments showed significant effects, with the maximum tuber yield (230.5 and 226.1 q ha^− 1 during the first and second years, respectively) recorded with the I₂ irrigation (4 irrigation stages), followed by I₃ (5 irrigations) and I₁ (3 irrigations). The greatest potato yield (239.0 and 234.2 q ha^− 1 during the first and second years, respectively) was observed with A₂. Significant interaction effects between different irrigation schedules and AAB treatments were found, with the highest interaction effect on tuber yield (255.0 and 241.3 q ha^− 1 during the first and second years, respectively) recorded with the I₂A₂ combination, followed by other treatment combinations. The impact of the irrigation schedule on nutrient uptake and tuber quality was found to be insignificant. These findings suggest that foliar application of AAB can improve nutrient use efficiency (NUE) by facilitating easier nutrient absorption and enhancing potato tuber quality.