Effects of foliar-applied fulvic acids on yield, biomass distribution, and nitrate accumulation in hydroponically grown radish (Raphanus sativus L.)

Abstract

Fulvic acids are humic-derived biostimulants that can modulate nutrient uptake, carbon metabolism, and biomass allocation in horticultural crops; however, their effect on assimilate partitioning and nitrate accumulation in hydroponically grown root vegetables remains poorly understood. This study evaluated the effect of weekly foliar application of a fulvic acid-based biostimulant (K-TIONIC®, 4 mL L–1) on yield, biomass distribution, nitrate content, and quality of radish (Raphanus sativus L. Crimson Giant) cultivated in an ebb-and-flow hydroponic system under greenhouse conditions in Chihuahua, Mexico. A completely randomized design with two treatments (control and fulvic acids) and 36 experimental units per treatment was used. Fulvic acid application increased equatorial diameter by 8.50%, fresh storage root weight by 28%, and total yield by 41.66%. In contrast, vegetative growth parameters and photosynthetic pigments were unaffected. Regarding quality attributes, nitrate concentration in edible tissues decreased by 4.96% and water content by 0.57%,  pH, total soluble solids, color index were not significantly affected, and visual quality index improved by 98%. These results indicate that foliar-applied fulvic acids improve radish productivity and commercial quality in soilless systems primarily by promoting biomass distribution  to the storage organ.