Dynamics of the indigenous microflora inhabiting the root zone and thenutrient solution of tomato in a commercial closed greenhouse system

摘要

In a commercial closed hydroponic greenhouse system, the microflora inhabiting the root and the nutrient solution of peat and rockwool grown tomato were studied on the basis of viable count (colony forming units, CFU), functional diversity using sole carbon source utilization (SCSU) patterns and taxonomic diversity using phospholipid fatty acid (PLEA) profiles. Sampling was done during one growing season, from May to October. Viable count of bacteria inhabiting the roots showed that the number of general bacterial flora and of fluorescent pseudomonads was higher in rockwool than peat while the amount of general fungal microflora, actinomycetes and Trichoderma was higher in peat than in rockwool grown tomato plants. For the irrigation effluent, no significant differences were found with respect to the general bacterial flora. The number of fluorescent pseudomonads decreased during the observation period whereas the number of actinomycetes rose towards the end of the experiment. For the general fungal flora and Trichoderma, viable counts showed significantly lower CFU for the samplings in August and September compared with the other sampling incidents. Furthermore, SCSU patterns and PLFA profiles showed differences in the root microflora with respect to growing medium and to sampling incidents. A separation of the microflora inhabiting the nutrient solution between the sampling incidents could also be done. This indicates that all three methods showed that the composition and the function of the microflora inhabiting the root and the nutrient solution shifted during the growing season and were different with respect to the growing medium.