@article{
author = "Mrkovački, Nastasija and Marinković, Jelena and Čačič, Nikola and Bjelić, Dragana",
year = "2010",
abstract = "The nonsymbiotic N fixing azotobacter
is an obligate aerobe living in the soil, the
rhizosphere and the plant root. The ability of
various strains to fix atmospheric N positively
affect plant growth and yields. Microbial
interactions with roots may involve either
endophytic or free living microorganisms and can
be symbiotic, assosiative or casual in nature.
Associative and free living microorganisms may
also contribute to the nutrition of plants through a
variety of mechanisms including direct effects on
nutrient awailability (N2-fixation), enhancement of
root growth (PGPR – plant growth promoting
rhizobacteria) as antagonists of root pathogenes
or as saprophytes that decompose soil detritus and
subsequently increase nutrient availability
through mineralization and microbial turnover.
Therefore, the abundance of azotobacter, fungi,
actinomycetes and the total number of
microorganisms in inoculated and non-inoculated
sugar beet rhizosphere were determine in this
study. Simultaneously we studied the effects of
application of nitrogen fertilizer, manure and
harvest residues. Samples of rhizosphere soil were
taken three times in the course of growing season
(May, July, September). The experiment included
two variants (inoculated with Azotobacter
chroococcum and non-inoculated) at four
fertilization levels (non-fertilized control, 50, 100,
150 and 200 kg N/ha), in five replication. Total
number of microorganisms was determined in soil
agar (dilution of 106
). Fungi were determined on
Chapek agar (dilution of 104
), actinomycetes on a
synthetic agar (dilution of 104
) and azotobacters
on Fiodor substrate (dilution of 102
). The results
of the study for all four fertilization types and all
four levels of added N showed that azotobacter
abundance was higher in inoculated treatments
than in the non-inoculated ones. The highest
increases of total microbial abundance and
number of free N-fixing bacteria were recorded in
the inoculated treatments with NPK fertilizer
alone and in the inoculated treatments with 100 kg
N/ha. The highest percentage increases of
azotobacter were obtained in the inoculated
treatments with manure and manure plus harvest
residues, respectively and in the variant without
N.",
publisher = "Timisoara : Banat´s University of Agricultural Science and Veterinary Medicine "King Michael I of Romania", Faculty of Agriculture",
journal = "Research Journal of Agricultural Science",
title = "Microbial abundance in rhizosphere of sugarbeet in dependance of fertilization and inoculation with Azotobacter chroococcum",
pages = "264-260",
number = "3",
volume = "42",
url = "https://hdl.handle.net/21.15107/rcub_fiver_2542"
}
