Interactive Effects of Humic Acid and Seaweed Extract on Growth, Yield and Quality of Tomato (Solanum lycopersicum L.)
Abstract
Background: Tomato (Solanum lycopersicum L.) productivity and fruit quality are strongly influenced by nutrient availability and crop-management practices. Humic acid and seaweed extract are plant biostimulants that may enhance vegetative growth, yield, and quality when applied at appropriate concentrations. Aims: This study evaluated the individual and interactive effects of foliar-applied humic acid and seaweed extract on the growth, yield, fruit quality, and economic performance of tomato (Solanum lycopersicum L.) cv. Arka Samrat. Place and Duration of Study: The experiment was conducted at the Agricultural Research Farm, Suresh Gyan Vihar University, Jaipur, during the Rabi season of 2025–26. Methodology: The experiment was laid out in a factorial randomised block design with two factors: humic acid at four concentrations (0, 2, 4, and 6 mL/L) and seaweed extract at four concentrations (0, 2, 4, and 6 mL/L). The 16 treatment combinations were replicated three times, and the observed data were analysed using OPSTAT. Results: Significant differences were observed among the treatments. Among the treatment combinations, humic acid at 4 mL/L combined with seaweed extract at 4 mL/L (M3T3) recorded the greatest plant height (312.62 cm), number of branches per plant (9.07), plant spread (65.92 cm), number of leaves per plant (69.13), number of clusters per plant (11.80), and number of flowers per cluster (9.01). It also recorded the fewest days to first flowering (27.69), 50% flowering (36.96), and first fruiting (41.95), together with the greatest number of fruits per cluster (8.24), average fruit weight (109.73 g), fruit yield per plant (6.40 kg), number of fruits per plant (58.35), total soluble solids (4.99 °Brix), ascorbic acid content (26.68 mg/100 g), and benefit–cost ratio (2.97). Conclusion: The treatment combination of humic acid at 4 mL/L and seaweed extract at 4 mL/L (M3T3) produced the most favourable growth, yield, quality, and economic responses under the conditions of this experiment. However, these findings are indicative and require further experimentation across seasons and locations before broader recommendations can be made.