Removing Inedible Seed Hulls Using Weighted Covers on Two Varieties of Sunflower (Helianthus annuus) Microgreens (Black Oil and Gray Striped) Grown Hydroponically on Burlap

Abstract

Microgreens, a highly nutritious crop, can be grown hydroponically on burlap to provide a more efficient production system. Sunflower (Helianthus annuus) microgreens have an inedible seed hull that typically falls off when grown in soil. In hydroponics, the seed hulls must be removed by growers manually, often leaving damage on the plant, which reduces the crop’s quality and profitability. As hydroponic technology is still new, there are limited scientific publications addressing this specific challenge. This study’s goal was to test the efficacy of weighted covers in reducing the number of seed hulls attached to H. annuus microgreens. 
Covers with varied weight (25 and 50 kg per meters squared) and different varieties of H. annuus seeds, Black Oil (BO) and Gray Striped (GS), were tested. Seeds were grown in researchers’ homes using mini desktop systems near windows. The BO variety outperformed GS in quality (p=0.00015) and yield (p=0.0425) when 50 kg per meters squared weight was used on the cover. The number of attached seed hulls for BO was fewer than that of GS, regardless of the weight of covers. The control group with darkness but no weighted covers had, on average, 12% more seed hulls attached than with weighted covers. Increasing the weight of the covers reduced seed hull attachment, but the higher weight also decreased the yield. The collected data indicate that BO may be better suited for hydroponics. Further research should include details of quality factors, such as chlorosis, necrosis, and injury.