EFFECT OF DIFFERENT SOILLESS GROWING SYSTEMS ON BIOLOGICAL PROPERTIES OF GROWTH MEDIA IN STRAWBERRY

The search for other substrates in soilless growing systems (SGS) can improve the sustainability of these systems. Using a randomized complete block design with three replicates, the following growed media were compared in three systems: growth media compared were a composted cork thin waste mixed with rice hulls (2:1, v:v) (CCR) and a peat substrate (P) in an open system (O), closed system (C) and closed with disinfection by slow sand filtration systems (CSSF). The microbial activities were determined by the measurement of the -glucosidase activity and the measurement of the hydrolysis rate of fluorescein diacetate (FDA). The microbial biomass was determined by acridine orange direct counting (AODC). The microbial community profile was determined by dilution plating on semi-selective media. The values of the activity measured by FDA and microbial biomass were higher in CCR than in peat at the beginning of the trial and at two and a half months after transplantation. At the beginning of the trial the activity measured by -glucosidase was higher in CCR than in P. With regard to growth media chemical properties, the CCR showed a higher pH and electrical conductivity than P, at the beginning and at two and a half months after transplantation. The CSSF showed a lower activity and lower density of copiotrophic bacteria and fungi than the O. The values of the activity measured by -glucosidase and microbial biomass were higher in the rhizosphere than in non rhizosphere of strawberry plants.