Abstract
Our objectives were to quantify the growth and tissue mineral nutrient concentrations of cilantro (Coriandrum sativum ‘Santo’), dill (Anethum graveolens ‘Fernleaf’), and parsley (Petroselinum crispum ‘Giant of Italy’) in response to nutrient solution electrical conductivity (EC) under low and high photosynthetic daily light integrals (DLI). Three-week old seedlings of cilantro, dill, and parsley were transplanted into nutrient-film technique hydroponic systems with one of five nutrient solution EC treatments (0.5, 1.0, 2.0, 3.0, or 4.0 dS·m−1) in greenhouses under a low (~7.0 mol·m−2·d−1) or high (~18.0 mol·m−2·d−1) DLI. The DLI, but not nutrient solution EC, affected culinary herb growth. For example, fresh mass increased by 21.0 (154%), 17.1 (241%), or 13.3 g (120%) for cilantro, dill, and parsley, respectively, for plants grown under high DLI compared to those grown under a low DLI; dry mass followed a similar trend. Tissue nutrient concentrations were generally affected by either DLI or EC. For those nutrients affected by DLI, concentrations increased with increasing DLI, except for potassium (K; all species) and manganese (Mn; dill). For those nutrients affected by EC, Ca and Mg decreased with increasing EC, while the remaining increased with increasing EC. When our tissue nutrient data are compared to recommended tissue concentrations, the vast majority of elements were either within or above recommended tissue ranges for cilantro, dill, and parsley. Our results demonstrate cilantro, dill, and parsley can be successfully grown across a range of EC, regardless of the light intensity of the growing environment.
Highlights
Culinary herbs are widely used to enhance the flavors of foods during cooking [1]
The nutrient concentration in solutions varying in electrical conductivity (EC) under low and high daily light integrals (DLI) changed between the initiation and termination of the experiment (Table 1)
While Mg and S concentrations decreased over the course of the experiment, reductions in Mg at higher EC values and in S concentrations at all EC treatments were more pronounced under the high DLI compared to identical solutions in the low DLI
Summary
Culinary herbs are widely used to enhance the flavors of foods during cooking [1]. While they are grown in fields for large-scale production and processing, fresh-cut culinary herbs are increasingly grown under protection for year-round and value-added crop production [2]. Culinary herb production in protected culture, including greenhouses, has been increasing concomitantly with the increased popularity in fresh-cut culinary herbs [3,4,5]. Of the several environmental factors affecting hydroponic culinary herb production, temperature and humidity are generally more favorable and managed in controlled environments compared to outdoor field environments; mineral nutrition and photosynthetic light must be more actively managed to stimulate plant growth and development [6]. Nutrient solutions are recirculated and the pH and electrical conductivity (EC) are Agronomy 2019, 9, 389; doi:10.3390/agronomy9070389 www.mdpi.com/journal/agronomy
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