Agriculture Reference
In-Depth Information
the biofertilizer, but is also the indicative of a number of phenomena, i.e., intensification of
photosynthesis process, inhibition of phytopathogens development, synthesis of
phytohormones (Sukhovitskaja et al., 2004), and other plant growth stimulators, targeted
detoxification of heavy metals and high salt concentrations, and exocellular polysaccharide
synthesis (Park et al., 2005; Biari et al., 2008). On the other hand, t h e biofertilizer greatly
reduced the number of soil fungi and actinomycetes, probably due to the fact that it consists
of strains that can produce antifungal substances. Many of these introduced microorganisms
can act like biocontrol agents by controlling or suppressing soil-borne plant pathogens
through their competitive and antagonistic activities (Higa and Parr, 1994). Therefore, the
decrease in the number of the soil fungi can be attributed to the ability of
Azotobacter
to
produce a certain antifungal substance which inhibits the growth of certain soil fungi.
Based on the number of the microorganisms in the soil from the pots used for growing
the different strawberry cultivars, the results of our experiment showed that the cultivar
significantly affected only the number of
Azotobacters
and oligonitrophils. According to
Antoun and Prevost (2005), plant genes play an important role in the interaction between the
plant and beneficial microorganisms. Smalla et al. (2001) reported rhizosphere populations of
strawberry that were considerably different from those of oilseed rape and potato. Smith and
Goodman (1999) also emphasize that the plant genotype affects the response to inoculation
with PGPR because it affects root colonization by the introduced bacteria, as well as the total
population size of microbial communities on plant and it probably affects the composition of
these communities.
Generative Potential and Fruit Quality Traits
Generative Potential
Crop growth and development are closely related to the nature of the soil microflora,
especially those in the close proximity to plants roots, i.e., the rhizosphere (Higa and Parr,
1994).
Due to
the fact that biofertilizers contain living microorganisms' cells, they improve the
soil composition and supply of essential nutrients for increasing productivity (Pešaković et
al., 2013). PGPR may induce plant growth by direct or indirect modes of action (Kloeper,
1993; Glick et al., 1999; Persello-Cortieaux et al., 2003). Direct mechanisms include fixation
of atmospheric nitrogen, solubilization of minerals such as phosphorus, production of
siderophores that solubilize and sequester iron or production of plant hormones that enhance
plant growth. Indirect effects are reflected in the fact that PGPR can promote plant growth by
improving growth restricting conditions, either by producing antagonistic substances or by
inducing resistance to pathogens (Glick, 1995; Glick et al., 1999).
With regard to the generative potential, results suggested that t h e applied biofertilizer
induced a higher number of fruits per plant as well as yield per plant. Investigations on the
effects of PGPR on yield and some fruit properties of strawberry showed a significant yield
increase in the 'Selva' cultivar (Lütfi and Murat, 2009). Güneş et al. (2009) reported similar
results in their study of the effects of phosphate-solubilizing microorganisms (
Bacillus
FS-3,
Aspergillus
FS9) on the strawberry yield and nutrient concentrations.
In order to investigate
the effects of the biofertilizer and bioregulators
on the growth, yield and nutrient status of
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