Fertilization and Pre-Sowing Seed Soaking Affect Yield and Mineral Nutrients of Ten Microgreen Species

Tongyin Li,Guihong Bi,Geoffrey T Lalk

doi:10.3390/horticulturae7020014

Abstract

Microgreens, vegetable or herb seedlings consumed at a young growth stage, are considered to be a functional food with high concentrations of mineral nutrients and healthy beneficial bioactive compounds. The production of microgreens has been increasing in recent years. Vegetable growers are interested in growing microgreens as a new specialty crop due to their high market value, popularity, and short production cycles. However, there is a lack of research-based crop-specific recommendations for cultural practices including fertilization, pre-sowing seed treatments, and their effects on nutritional facts of microgreens. Ten microgreen species were evaluated for their shoot growth and mineral nutrient concentrations as affected by one-time post-emergence fertilization and pre-sowing seed soaking in two repeated experiments, from November 2018 to January 2019, in a greenhouse. The microgreen species varied in fresh and dry shoot weights, shoot height, visual rating, as well as macro- and micro-nutrient concentrations. Fertilization with a general-purpose soluble fertilizer (20-20-20 with micronutrients) at a rate of 100 mg·L−1 nitrogen (N) increased fresh shoot weight, and macro- and micro-nutrient concentrations in one or both experiments, with the exception of decreasing concentrations of calcium (Ca), magnesium (Mg), and manganese (Mn). Seed soaking consistently decreased fresh or dry shoot weight and nutrient concentrations when there was a significant effect.

Highlights

Microgreen is a collective term used for vegetable or herb seedlings consumed at a young growth stage, with expanding cotyledons or the first pair of true leaves, harvested7 to 21 days after germination [1,2,3,4]
The objective of this study was to investigate the effects of pre-sowing seed soaking and post-emergence fertilization on shoot growth and mineral nutrients of ten microgreen species
The ten tested microgreen species varied in their yields in terms of fresh and dry shoot weights, consistent with reported ranges [3,16,23,24,25]

Summary

Introduction

Microgreen is a collective term used for vegetable or herb seedlings consumed at a young growth stage, with expanding cotyledons or the first pair of true leaves, harvested7 to 21 days after germination [1,2,3,4]. The market value of microgreens is 30 to 50 USD per pound [7], drawing interest among vegetable growers for the high value and short production cycles [8]. Microgreens are considered to be a functional food and have high concentrations of mineral nutrients and phytochemicals that contribute to health benefits [11,12]. Microgreens in the Brassicaceae family are rich sources of mineral nutrients including potassium (K), Ca, iron (Fe), and zinc (Zn) [5,13]. Brassica microgreens have high contents of healthy phytochemicals including ascorbic acid, phylloquinone, carotenoids, tocopherols, glucosinolates, and polyphenols [15]. Cultural practices including pre-sowing seed treatments, seeding rate, and fertilization, along with the microenvironment including temperature, light, and growth medium may all affect yield and nutrient compositions of microgreens [3,9,16,17]

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Results

Discussion

Conclusion