SEASONAL VARIATIONS OF BIOTIC FACTORS IN CLOSED COMMERCIAL GREENHOUSE GROWING SYSTEMS WITH TOMATO

Biotic factors (general bacterial and fungal microflora, fluorescent pseudomonades, actinomycetes, and selected pathogens) were monitored in the nutrient solution of three commercial greenhouse nurseries growing tomatoes in closed systems during the growing season.
All three used different disinfestation technologies for reducing the dispersal of root pathogens by the recirculating nutrient solution (slow filtration, multi-layer filtration, oxidation with advanced oxidation technologies, AOT). Supporting variables such as total organic carbon (TOC) content and chemical oxygen demand (COD), oxygen content, temperature, pH and electrical conductivity were measured.
Microbial community patterns using sole carbon source utilization (SCSU) and phospholipid fatty acid profiles (PLFA) were done for the system using slow filtration.
The general fungal and bacterial flora, pH and oxygen content in the effluent nutrient solution were found to be useful predictors for the crop’s developmental stage (R²=74.8%; p<0.001). Individual changes in biotic and supporting factors occur depending on the design of the growing system.
Both patterns of SCSU and PLFA profiles indicated shifts in the composition and the function of the microflora inhabiting the nutrient solution during the growing period.
A correlation (R²=95.7%) between TOC and COD was established.

International Symposium on Growing Media 2007

K.-J. Bergstrand, S. Khalil, M. Hultberg, B.W. Alsanius

chemical oxygen demand, COD, hydroponics, microflora, phospholipids fatty acid analysis, PLFA, sole carbon source utilization, SCSU, total organic carbon content

https://doi.org/10.17660/ActaHortic.2009.819.20