مشخصات پژوهش

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