Morphological and Qualitative Response of Carrot (Daucus carota) to Foliar Application of Iodine in southern Guinea Savannah Zone of Nigeria

Carrot is an important vegetable in Nigeria which is cultivated mainly in the Savannah zone. The region suffers from iodine-deficient soils due to its mountainous terrains, valleys, and distance from the ocean. This, coupled with the lack of access to seafood, exacerbates iodine deficiency, leading to conditions such as goitre, impaired cognitive function, and lower fertility in humans and plants. The objectives of this study were to evaluate the effects of foliar-applied iodine levels on growth performances and yield of carrot. Field experiments were conducted at the Teaching and Research Farm, University of Ilorin, Ilorin - Nigeria during 2023 and 2024 cropping seasons using randomized complete block design (RCBD) with four replicates. Treatments were foliar applied potassium iodate (KIO₃) at rates of 0, 3.5, 7.0, 10.5, 14.0 kgha^-1. Data on plant growth and yield were collected. Analysis of variance was carried out and means were separated by least significant difference (p≤0.05). The application of 14 kg ha⁻¹ iodine resulted in the highest iodine and β-carotene contents in carrot tubers in both cropping seasons. The same application rate also produced the highest tuber yield during the first cropping season and the highest plant height during the second cropping season. Application of 10.5 kgha^-1 demonstrated the highest shoot dry matter content in both seasons and the highest tuber yield during the second season. However, increased iodine levels reduced the chlorophyll content in both seasons. The study suggests that foliar application of iodine can improve carrot growth, yield, and nutritional quality. Further research across multiple cropping seasons is recommended to determine the optimum iodine dosage for carrot cultivation.