Nitrogen Concentration Affects Nutrient and Carotenoid Accumulation in Parsley

Previous research has suggested that the herbal crop parsley (Petroselinum crispum Nym.) has a relatively high concentration of nutritionally important carotenoid phytonutrients, such as lutein-zeaxanthin and β -carotene. Nitrogen (N) has the most direct impact on plant growth, but influence of N on phytonutritional quality is contradictory. Therefore, the objectives of this study were to measure the effects of different concentrations of N on growth, elemental accumulation, and carotenoid production in parsley. 'Dark Green Italian' parsley was greenhouse-grown in a nutrient solution with 6.0, 13.1, 26.3, 52.5, or 105.0 mg N L^-1. After 8 weeks, plants were harvested and analyzed for biomass production, micro- and macronutrient concentrations, and lutein-zeaxanthin and β -carotene levels. Increasing N in the nutrient solution increased plant biomass, leaf tissue N, phosphorus (P), potassium (K), lutein-zeaxanthin, β -carotene, and chlorophyll. Leaf iron (Fe), manganese (Mn), and molybdenum (Mo) decreased with increases in N in nutrient solutions. Quadratic increases in response to increasing solution N occurred for leaf calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), and zinc (Zn). Increasing the elemental and carotenoid concentrations in parsley through N fertility modification would be expected to increase the nutritional value of this culinary herbal crop.