Morpho-quality response of tomato (Solanum lycopersicum L.) fruits to preharvest iodine applications

Abstract

Tomato is a nutritionally rich vegetable crop and is valued for its economic importance. It is one of the most widely cultivated vegetable crops globally after the potato. Despite its importance, tomato yield and quality are frequently constrained by hidden micronutrient deficiencies, as reported under diverse soil and agro-climatic conditions. The present investigation was conducted for two consecutive years to evaluate iodine application using two sources, potassium iodide (KI) and potassium iodate (KIO₃), through soil, foliar spray, seed priming, and their combinations. The experiment comprised nine treatments laid out in a randomized complete block design (RCBD) with three replications. Key parameters related to fruit morphology and quality attributes were measured to determine the efficacy. Integrated and foliar applications of KI, particularly T8 (SP+SA+FA) and T4 (FA), significantly enhanced fruit size (polar diameter up to 6.15 cm) and fruit weight per plant (1.89 kg). Quality traits, such as ascorbic acid content (29.40 mg/100 mL), TSS (5.51°Brix) and dry matter content (6.63%) were also markedly improved. Correlation analysis showed strong positive linkages between fruit size traits (polar and equatorial diameter, average fruit weight), yield and key quality attributes (ascorbic acid, TSS and dry matter), with PCA identifying these traits as major contributors to treatment variability. Although structural traits such as locules and seed number showed weaker correlations, the overall findings support the use of foliar KI @ 0.5 mg/l as an efficient, economical and practical approach for improving tomato fruit quality and physiological performance in North-Indian conditions.