Effect of organic growing system on microbial population in rhizosphere of medicinal and aromatic plant species

Abstract

The aim of this study was to compare abundance of microorganisms in the rhizosphere of four different medicinal and aromatic plant species (basil, mint, dill and marigold) grown under both conventional and organic management. The trials were set up on chernozem soil at experimental field of Bački Petrovac, Institute of Field and Vegetable Crops, Novi Sad (northern Serbia). Rhizosphere soil samples were collected in two sampling terms during 2015 (June 2 and July 28, 2015) and analysed by the indirect dilution method followed by plating of soil suspension on selective nutritive media. The obtained results showed significant differences in microbial abundance between plant species, growing systems and sampling terms. The highest number of azotobacters and cellulolytic microorganisms were obtained in rhizosphere of marigold, while total microbial number and fungi were the most abundant in rhizosphere of basil. The most common population of ammonifiers, free N-fixing microorganisms and actinomycetes were recorded in rhizosphere of dill. Significantly higher number of microorganisms was found in organic growing system compared to conventional, while the number of most tested microbial groups was higher at the first sampling period.