Agronomic biofortification with zinc in hydroponically cultivated lettuce

Abstract

Lettuce is the most cultivated leafy vegetable in hydroponic systems. The biofortification of lettuce with zinc (Zn) can contribute to relieving nutritional deficiencies in socially vulnerable populations. Biofortification is affordable, easy and fast, even in urban areas. Our objective was to evaluate the effect of Zn concentration in nutrient solutions on the production and agronomic biofortification of lettuce cultivars. The experimental design was completely randomized, in a split-plot design, with four replicates. We tested Zn concentrations of 0.3, 1.0, 1.7 and 2.4 mg L-1 in the hydroponic solution and the cultivars 'Vanda' and 'Saladela'. We evaluated plant diameter, number of leaves, fresh and dry mass of the aerial part and root, a chlorophyll index, Zn content and the accumulation of Zn in leaves and roots. 'Vanda' lettuce had the largest diameter, and 'Saladela' lettuce had the most leaves. The fresh mass of the aerial part was higher in 'Vanda' lettuce. For a Zn concentration of 2.4 mg L-1, the Zn contents of the leaves and roots were 733.3 and 2441 mg kg-1 and the accumulations of Zn in the leaves and roots were 931.66 and 4890 mg plant-1, respectively. Zn content and accumulation were higher in 'Saladela' lettuce. FM, DM did not decrease with increasing Zn concentration in the nutrient solution. Agronomically biofortifying the lettuce produced hydroponically using the nutrient film technique was thus possible