Inadequate intake of Fe and Zn is prevalent in a large part of the world’s population, and agronomic biofortification has been a strategy to improve the nutritional quality of food and, consequently, the nutrient intake by people. The objective of this study was to evaluate the effects of Fe and Zn concentrations in the nutrient solution on the morphophysiological traits, nutritional quality, and biofortification of two cultivars of baby leaf lettuce in a deep water technique hydroponic system. Two experiments were conducted, one with ‘Vanda’ lettuce (green) and the other with ‘Luminosa’ lettuce (reddish). Six treatments were evaluated, in a 3 × 2 factorial scheme, corresponding to the concentrations of Fe (2.0, 4.0, and 8.0 mg L⁻¹) and Zn (0.06 and 0.24 mg L⁻¹), with four replicates. ‘Vanda’ proved to be more productive, while ‘Luminosa’ has a higher nutraceutical value. The growth traits, yield, and leaf contents of carotenoids and anthocyanins of both cultivars were not influenced by the increase in Fe and Zn concentrations in the nutrient solution. There was a 25% and a 33% increase in the content of phenolic compounds in ‘Vanda’ and ‘Luminosa’, respectively, when the Fe concentration increased from 2 to 8 mg L⁻¹. The Fe content in ‘Vanda’ was influenced only by the Fe concentration in the nutrient solution and increased by 13% between 2 and 8 mg L⁻¹ of Fe. For ‘Luminosa’, there was an interaction, but the highest Fe contents in the shoot were observed with 8 mg L⁻¹ of Fe, which were 24 and 38% higher than those obtained with 2 mg L⁻¹ of Fe at Zn concentrations of 0.06 and 0.24 mg L⁻¹, respectively. The study showed the importance of evaluating the biofortification for cultivars. While ‘Vanda’ baby leaf was biofortified only with Fe, ‘Luminosa’ was biofortified with both micronutrients.

Planting density should be a priority in the improvement of the baby leaf cultivation technique, as it influences morphophysiological characteristics. This study aimed to evaluate seven planting densities (408-2,856 plants m^-2) on the growth, yield and quality of ‘Vanda’ baby leaf lettuce under floating hydroponic cultivation. Two experiments were carried out in a randomized block design, with four replicates. The leaf length had an initial increase followed by a decrease at the highest planting densities, whereas the fresh and dry masses decreased. The yield, in turn, increased 215 and 372 % between the lowest and highest planting density in the experiments 1 and 2, respectively. Regarding the baby leaf quality, the calcium and magnesium contents did not show a response pattern in the two growing seasons, whereas the potassium and zinc contents increased and the iron content decreased with the increase in planting density in both seasons. The vitamin C content increased, whereas the chlorophyll and carotenoid contents decreased with the increase in planting density.

Baby leaf aromatic–medicinal plants have been an interesting option for the ready-to-eat commercial segment because they have a short cycle, high yield and high density of bioactive compounds. In the floating cultivation of baby leaf coriander, planting density and harvest time still lack definition. In this context, an experiment was carried out in protected cultivation, in Jaboticabal, Brazil, to evaluate how these two factors affect the growth, yield and quality of baby leaf coriander, in a floating hydroponic system. This experiment was conducted in a randomized block design, in split-plots, with four replicates. Plots corresponded to harvest times (10 and 13 days after transplanting to the floating system, DATF), and subplots corresponded to planting densities (408, 816, 1224, 1632 and 2040 plants m⁻²). A delay in harvest increased the number of leaves and leaf blade, petiole and leaf lengths by 30, 19, 39 and 30%, respectively, in addition to leaf area, shoot fresh and dry masses and yield. The higher the planting density, the higher the values of growth characteristics. The maximum yield (1.091 kg m⁻²) was observed with 2040 plants m⁻² for harvest at 13 DATF. Later harvest increased the contents of carotenoids, vitamin C, calcium and zinc. Planting density did not alter the contents of phenolic compounds but increased calcium, iron and zinc contents. Thus, 2040 plants m⁻² associated with harvest at 13 DATF is recommended, as it favored yield and nutraceutical value.