Background The microbiome plays a fundamental role in plant health and performance. Soil serves as a reservoir of microbial diversity where plants attract microorganisms via root exudates. The soil has an important impact on the composition of the rhizosphere microbiome, but greenhouse ornamental plants are commonly grown in soilless substrates. While soil microbiomes have been extensively studied in traditional agriculture to improve plant performance, health, and sustainability, information about the microbiomes of soilless substrates is still limited.
Thus, researchers conducted an experiment to explore the microbiome of a peat-based substrate used in container production of Impatiens walleriana, a popular greenhouse ornamental plant. They investigated the effects of plant phenological stage and fertilization level on the substrate microbiome. Results Impatiens plants grown under low fertilization rates were smaller and produced more flowers than plants grown under optimum and high fertilization. The top five bacterial phyla present in the substrate were Proteobacteria, Actinobacteria, Bacteriodota, Verrucomicrobiota, and Planctomycetota. Researchers found a total of 2,535 amplicon sequence variants (ASV) grouped into 299 genera. The substrate core microbiome was represented by only 1.8% (48) of the identified ASV. Plant phenological stage and fertilizer levels influenced the microbiome community composition. Phenological stage exhibited a stronger influence on microbiome composition than fertilizer levels. Differential abundance analysis using DESeq2 identified more ASVs significantly affected (enriched or depleted) in the high fertilizer levels at flowering. As observed for community composition, the effect of the plant phenological stage on microbial community function was stronger than that of fertilizer level. Phenological stage and fertilizer treatments did not affect alpha diversity in the substrate.
In container-grown ornamental plants, the substrate serves as the main microbial reservoir for the plant, and the plant and agricultural inputs (fertilization) modulate the microbial community structure and function of the substrate. The differences observed in substrate microbiome composition across plant phenological stages were explained by pH, total organic carbon (TOC), and fluoride, and across fertilizer levels by pH and phosphate (PO4). The project provides an initial diversity profile of the bacteria occurring in soilless substrates, an underexplored source of microbial diversity.
Quijia Pillajo, Juan & Chapin, Laura & Quiroz-Moreno, Cristian & Altland, James & Jones, Michelle. (2024). Nutrient availability and plant phenological stage influence the substrate microbiome in container-grown Impatiens walleriana 'Xtreme Red'. BMC Plant Biology. 24. 10.1186/s12870-024-04854-7.