ASHS 2024 Conference

Plugs are crucial for starting crop production in greenhouses, soil, and controlled environment agriculture (CEA). Horticultural, vegetable, fruiting, and ornamental crops that utilize plugs for production have demonstrated better plant health, transplant establishment rate, and total yield. Many substances are capable of supporting plug growth, so the APS Laboratory for Sustainable Food at Florida Gulf Coast University investigated the quality of plugs prepared based on different commonly used growth mediums for plug production. We carried out the growth of Rex Butterhead Lettuce Latuca Sativa plugs with six different treatments: 1) Rockwool, 2) Oasis® Horticube, 3) Perlite 4) Coco Coir, 5) Phenolic Foam, and 6) Peat Pellets. The seeds were sowed in their respective growth medium and watered every day. The plugs were then cultivated for 15 days in a controlled environment until two leaves apart from the cotyledon had developed. After 15 days, we collected data which included wet weight (g), dry weight (g), leaf area (cm2), nitrogen content (mg/g), and chlorophyll concentration (mg/cm2). In addition, we derived data including the Leaf Area Index (LAI) and Specific Leaf Area (SLA, cm2/g). Descriptive statistics were used to describe the biomass data. Pairwise permanovas were conducted, followed by pairwise Wilcoxon tests to determine which treatments result in significant differences for each response variable. A permutation MANOVA revealed a significant treatment effect on plug preparation (p=0.001). All subsequent multilevel pairwise comparisons were significant, with the exception of phenolic foam vs perlite (p=0.294). Of all the treatments, we concluded that plugs grown in Peat Pellets produced the most viable plugs with the largest wet weight (g), dry weight (g), and total leaf area (cm2). Results from this study may inform growers about appropriate growth mediums for efficient plug production. Keywords: Controlled Environments, Growth Mediums, Lettuce, Plugs, Urban Agriculture