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Abstract
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Water stress is the most important environmental
factor that limits plant growth and yield. However, plant
growth-promoting rhizobacteria (PGPR) can stimulate
resistance of the plant host in unsuitable environmental
conditions such as water stress. In order to evaluate whether
PGPR improve morphological, physiological, and
phytochemical traits of the savory plant Satureja hortensis
L., the effects of two PGPR strains of Pseudomonas fluorescens
Migula (PF-135 and PF-108) under two water
conditions (well-watered and 50 % field capacity) were
studied by performing a factorial experiment based on
randomized complete block design with three replications
under commercial greenhouse. The highest values of root
and shoot dry matter, root length, plant height, leaf number,
and branch number were observed in PF-135-inoculated
plants under well-watered conditions, whereas the abovementioned
parameters were found to be the lowest in noninoculated
plants under water stress condition. Chlorophyll
a, b, total chlorophyll, and carotenoid contents significantly
changed under water stress conditions. The H2O2 and
MDA contents of root and shoot significantly decreased in
plants inoculated with PF-135, whereas their contents
increased in non-inoculated plants under water stress condition.
The highest shoot oil yield was observed in plants
inoculated with PF-135 under water stress condition, while
the lowest shoot oil yield was observed in plants inoculated
with PF-108 under well-watered condition. Twenty-eight
components were found in the essential oils of S. hortensis.
Carvacrol (56.81–78.15 %), c-terpinene (9.08–22.87 %),
and p-cymene (5.78–14.28 %) were identified as the major
components in all treatments. Plants under water stress
conditions showed the highest yield of these components
when inoculated with bacteria. Thus, we could suggest that
the promising strains of P. fluorescens are able to minimize
the deleterious effects of water stress on plant growth and
improve the morphol
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