Currently, however, there is not enough knowledge on the composition of the recirculated organic matter fractions and how these fractions affect the microbial composition, including plant pathogens and its interactions with the plant. Since these factors affect crop health, yield and safety, enhanced knowledge on the mechanisms for interaction will help improve crop performance as well as food safety.
Furthermore, it can direct applied treatments to selectively remove any problematic organic matter fractions. A study on rapid water quality parameters with water from horticulture showed that the addition of specific fractions of organic matter to the nutrient solution of substrate-grown tomatoes resulted in a more resilient microbial community in the rhizosphere. Microbial growth parameters (heterotrophic plate count (HPC) and ATP-analysis) indicated an increase in microbial activity in drain water compared to the nutrient solution. This work highlighted thatHPC provides a solid parameter to monitor water quality from feeding source to water treatment, but generating results with these method takes three days. In contrast, ATP measurements or flow cytometry provide similar insights within minutes.For effective and efficient assessment of crop performance and food safety, there is a need for rapid screening methods to gain insights in horticulture water quality.Using next-generation sequencing (NGS) we could find significant effects on the bacterial composition in the rhizosphere after addition of plant-pathogenic Fusarium oxysporum.
These findings highlight the potential to steer rhizosphere microbiology to maintain a healthy and safe cultivation system, but detailed information on the effects of specific fractions of organic matter is currently lacking.Overall, we conclude that water reuse has a great potential for a circular horticultural system, but that rapid and effective insights into the effects of recirculation water are crucial to guarantee crop performance in a closed irrigation system.Future research aims at developing rapid screening methods for microbiology and organic matter to be able to manage crop performance parameters for improved crop health and yield.
Source: Zandt, M. 2021. Novel insights and technologies for monitoring and improving water quality in a recirculating greenhouse system. Water quality and species monitoring, efficient water use and data-led solutions. Clean Water & Ecosystem Restoration. AIWW 2021.