Just in case you missed the buzz during the PCA conference in Brisbane, here is more useful information on iodine. Iodine is beneficial for yield and quality of fertigated crops. The role of iodine in plant nutrition and stress protection is now better understood (Kiferle et al. 2021). When included in potassium nitrate, iodine in the nutrient solution can help restore some of the yield-loss due to stress in tomato and sweet pepper in hot greenhouses  (3). Iodine helps calcium to translocate to fruits and improves fruit set by protecting the quality of pollen in flower buds under heat stress.


In tomato on rock wool, where chronic salinity stress was induced with NaCl, iodine effectively increased yield in number of fruits per truss/per plant and individual fruit weight, compared to plants with a minimal amount of iodine in the nutrient solution  (Kiferle et al. 2022). Notably, also in non-stressed plants, the presence of iodine in the nutrient solution increased plant growth and fruit yield and improved firmness of the fruit. The stress-mitigating mechanism of iodine in plants, is explained by an improved capacity to activate the antioxidant metabolism in the roots and leaves. In Australia, ask Elders about Ultrasol®ine K Plus, water soluble potassium nitrate with iodine to make it easy to provide the right dose for the crop in fertigation.


Hora, K. and Holwerda, H.T. (2023). Loss of yield or lower fruit quality due to iodine deficiency in tomato and sweet pepper crops under heat stress can be prevented by application of potassium nitrate with iodine. Acta Hortic. 1372, 251-258 https://doi.org/10.17660/ActaHortic.2023.1372.33

Kiferle, C.,  Martinelli, M., Salzano, A.M., Gonzali, S., Beltrami, S., Salvadori, P.A., Hora, K.,  Holwerda, H.T., Scaloni, A., Perata, P. (2021). Evidences for a nutritional role of iodine in plants. Frontiers in Plant Science 12:616868. https://www.frontiersin.org/article/10.3389/fpls.2021.616868

Kiferle, C., Gonzali, S., Beltrami, Martinelli, M., Hora, K., Holwerda H.T. & Perata P. (2022_. Improvement in fruit yield and tolerance to salinity of tomato plants fertigated with micronutrient amounts of iodine. Sci Rep 12, 14655. https://doi.org/10.1038/s41598-022-18301-w