Influence of potassium iodate and chitosan iodate complex on growth, yield, quality and iodine uptake in ‘shivam’ hybrid of tomato (Solanum lycopersicum L.)

Abstract

An iodine biofortification experiment was conducted by applying potassium iodate fertilizer in soil and foliar form and chitosan complex forms to investigate the growth, yield, quality and uptake of iodine in shivam hybrid of tomato in Palaviduthi soil series of Coimbatore region. Soil fertilization alone resulted in lower uptake of iodine in fruits because the iodine is susceptible to high volatilization and less phytoavailability and also resulted in less yield and poor quality of fruits. When the chitosan and potassium iodate were applied in combination through foliar form, the quality of the fruits was found to be superior (carotene-1.24 mg 100gm-1 ascorbic acid-3.56 mg 100gm-1, titrable acidity-0.96%), with higher fruit yield (94.81 t ha-1) and uptake of iodine in fruits (0.99ppm). Potassium iodate alone, either in the form of soil or foliar application, increased the quality of fruits, but it did not prevent the loss of various pigments and acids during ripening and also the loss of iodine through volatilization. But chitosan conserved the losses by reducing the respiration rate and oxygen permeability. Further, chitosan formed an electrostatic interaction with potassium iodate, preventing volatilisation and gradually increasing the bioavailability of iodine from soil to fruits. Hence biofortifying iodine in the form of potassium iodate chitosan complex was preferred for enhancing yield, improving quality and increasing the iodine content in fruits.