Environmental Control in the Plant Factory System Influences Year-Round Production of Allium hookeri Leaves

Abstract

The demand for the fresh leaf of hooker chive, which is mainly used as functional roots and contains dietary sulfur or saponin, is increasing, but the leaves are only harvested 3-4 times per year under conventional field conditions. A plant factory system with different light qualities or intensities was applied for year-round production of the fresh leaves. Hooker chive (Allium hookeri) roots were hydroponically cultured under the plant factory with a mixture of blue plus red LEDs (Light-Emitting Diodes) and fluorescent lights for 50 weeks. Maximum leaf growth was attained with the 1.5 dS/m EC in the culture medium under the plant factory. The average leaf and shoot numbers of hooker chive grown hydroponically under a mixture of 200 μmol/m 2 /s LEDs increased by 147% and 140%, respectively compared to those under 100 μmol/m 2 /s LEDs at the 10th harvest. The leaf length of hooker chive grown under the LEDs treatment with the lowest light intensity significantly increased by 27% compared with the natural light treatment at the 10th harvest. However, there was no significant difference in leaf pigmentation between natural and 200 μmol/m 2 /s LEDs treatments. Plant factory with the mixture LEDs of blue and red lights can be applied for year-round production of hooker chive fresh leaves to ensure a stable supply of leafy vegetable throughout the year.