Integrative traceability with path analysis demonstrates iron-mediated effects on tomato ( Solanum lycopersicum ) development and quality

Iron (Fe) plays a crucial role in plant physiological and biochemical functions impacting the yield and quality of tomato. The direct and indirect effects on development, yield and quality attributes remain poorly quantified, despite abundance of iron in soil. A two-year field study was conducted at Punjab Agricultural University, Ludhiana using 12 iron fertilization strategies employing randomized complete block design with three replications to access the impact of different sources and method of iron application on vegetative growth, yield attributes and quality parameters of tomato. Combined application of FeSO4.7H2O through seed priming + soil + foliar application markedly enhanced growth (plant height: 110.35 cm; canopy width: 47.23 cm) and fruit set (26.56 fruits plant−1), achieving 2.15 kg plant−1, a 25.3% gain over control. Foliar FeSO4.7H2O showed highest total yield (579.78 q ha−1), while Combined application of FeSO4.7H2O through seed priming + soil + foliar application secured the maximum marketable yield (499.08 q ha−1 vs. 435.80 q ha−1 in control). Quality attributes improved significantly under iron supplementation with ascorbic acid (32.35 mg 100 ml−1), titratable acidity (0.91%), and TSS (6.06°Brix) surpassing control values. Advanced trait analyses revealed early flowering (–1.610), polar diameter (1.640) and dry matter (1.534) as decisive yield drivers. Economic feasibility was also evident with B:C ratio of 2.82–2.83 with combined and foliar strategies again 2.44 in control. Collectively, the findings highlight foliar iron fertilization as a novel, sustainable production strategy to enhance tomato yield, fruit quality particularly under the agro-climatic conditions of North Indian plains.