Plants Dictate Root Microbial Composition in Hydroponics and Aquaponics

Abstract

The role of the microbial community in mediating fish and plant co-culture is often considered the black box of aquaponics. Despite widespread recognition regarding the dependency of plants on their rhizosphere, the extent to which upstream aquaculture influences downstream hydroponic root communities has been poorly described in the literature. In this study we performed a taxonomic survey (16S rRNA metabarcoding) of microbial communities originating in the facility water source, hydroponic nutrient solution (HNS) sump, nutrient supplemented biofilter effluent (BF) sump, and recirculating aquaculture system tanks stocked with Nile tilapia (Oreochromis niloticus). Lettuce (Lactuca sativa) was then grown using the HNS and BF effluent under sterilized or mature (prior aquaponics/hydroponics lettuce culture water) conditions, likewise, the influence of probiotic addition or inoculation with soil-grown lettuce rhizosphere was assessed. Compositional similarities across treatments suggest that under soil-less conditions, plants are able to exert a stronger discriminatory influence on their rhizosphere composition than is done by colonization from upstream sources. Furthermore, cluster dendrograms grouped the sterilized and unsterilized treatments more consistently together than hydroponics and aquaponics treatments. These findings contradict conventional beliefs that microbial communities in the water column colonize roots based on their presence alone, ignoring the role that plants play in rhizosphere community selection.

Spearmint enhances lettuce biomass and provides microbes to co-cultured lettuce in a decoupled aquaponic system

“…The present study revealed that the bacterial community in mature lettuce did not develop markedly from the RAS e uents. It has been shown in a soilless system that the plant played a more important role in determining the rhizosphere microbial community than the microbes in water (Lobanov et al 2022). Our results support the ndings of Lobanov et al (2022) as in our system the microbial communities in the lettuce were affected by the co-cultured plant species, but showed negligible transfer of bacteria from the RAS e uents to the lettuce.…”

Hormetic Effect of Wood Distillate on Hydroponically Grown Lettuce

“…In our case, it is evident that WD proved to be an excellent solution for increasing the fresh weight of plants, but also the development and growth of the roots. Specifically, the root system plays a fundamental role in the growth of plants in hydroponics, which is even more important than in traditional soil growing [37]. Our results clearly show that the addition of WD to the nutrient solution showed a hormetic effect depending on the concentration used.…”

Effect of Fertigation with Struvite and Ammonium Nitrate on Substrate Microbiota and N2O Emissions in a Tomato Crop on Soilless Culture System

“…The microbiome diversity in soil and soilless tomato crops is likely to be different due to the different growing conditions and substrate types, as has been demonstrated by several authors [11,74,75], suggesting a facility-specific microbiome form within the rhizosphere for hydroponics systems, as well as other growing media [76,77]. Moreover, under soilless conditions, plant species can exert a stronger discriminatory influence on their rhizosphere composition [78]. Even the microbiology of the hydroponics rhizosphere and the substrate's effect remain understudied; to discuss our microbial community structure, we are going to mainly focus on soilless culture and/or tomato literature.…”