The Hydroponic Rockwool Root Microbiome: Under Control or Underutilised?

Abstract

Land plants have an ancient and intimate relationship with microorganisms, which influences the composition of natural ecosystems and the performance of crops. Plants shape the microbiome around their roots by releasing organic nutrients into the soil. Hydroponic horticulture aims to protect crops from damaging soil-borne pathogens by replacing soil with an artificial growing medium, such as rockwool, an inert material made from molten rock spun into fibres. Microorganisms are generally considered a problem to be managed, to keep the glasshouse clean, but the hydroponic root microbiome assembles soon after planting and flourishes with the crop. Hence, microbe–plant interactions play out in an artificial environment that is quite unlike the soil in which they evolved. Plants in a near-ideal environment have little dependency on microbial partners, but our growing appreciation of the role of microbial communities is revealing opportunities to advance practices, especially in agriculture and human health. Hydroponic systems are especially well-suited to active management of the root microbiome because they allow complete control over the root zone environment; however, they receive much less attention than other host–microbiome interactions. Novel techniques for hydroponic horticulture can be identified by extending our understanding of the microbial ecology of this unique environment.

The edible plant microbiome: evidence for the occurrence of fruit and vegetable bacteria in the human gut

“… 26 , 27 However, these cultivation methods also potentially decrease bacterial diversity in fruits and vegetables due to poor microbial complexities in the production environment in comparison to natural soil systems. 28 , 29 An interesting perspective would be to improve microbial diversity in the media used to grow plants in order to not only fulfill beneficial functions for the plant but also for humans consuming them.…”

Evaluating Organic Fertilizers and Microbial Inoculation for Soilless and Hydroponic Crop Production

“…When organic fertilizers are used, many nutrients bound within organic substances are not readily accessible for direct plant uptake, necessitating microbially mediated mineralization processes to release the nutrients (Bergstrand et al 2020;Burnett et al 2016). However, sterile and inert soilless substrates, such as rockwool, typically lack a robust microbial community, making it challenging to provide adequate and accessible nutrients during soilless and hydroponic crop cultivation (Grunert et al 2016;Shinohara et al 2011;Thomas et al 2023).…”