EFFECT OF FOLIAR IRON RATES AND APPLICATION TIMING ON LETTUCE (Lactuca sativa L.) BIOFORTIFICATION IN AN NFT HYDROPONIC SYSTEM

Resumen

Iron (Fe) is an essential micronutrient for living organisms and plays a key role in numerous physiological processes. Agronomic biofortification with Fe can increase its concentration in edible plant tissues, representing a promising strategy to improve dietary Fe intake and help prevent iron-deficiency anemia, particularly in vulnerable populations. Two experiments were carried out in winter and summer to evaluate the effects of foliar iron application on hydroponically grown lettuce (Lactuca sativa L.) cv. ‘Waldmann’s Green’ at three concentrations (2, 4, and 6 mg L^-1) and three application timings: 100% at 10 days after transplant (DAT); 100% at 20 DAT; and 50% at 10 DAT plus at 20 DAT. Production of leaf fresh and dry weight, root fresh and dry weight, and foliar N, P, K and Fe were evaluated. A randomized complete block design was used, with a 3x3+1 factorial arrangement, with five replications per treatment. Analysis of variance was performed for winter and summer experiments plus a combined analysis of both experiments. Fe rates or application timings did not affect fresh and dry matter contents of leaves or roots. However, the growing season significantly affected root fresh and dry matter content. N, P and K foliar concentrations were influenced by Fe application rates and timings, with significant variations between growing seasons. Efficient Fe biofortification in lettuce leaves was observed starting at 4 mg L^-1 of Fe, being higher in summer.