Combination between plant growth promoting rhizobacteria; Pseudomonas fluorescensand mycorrhizal fungi AM (Glomusmosseae) were applied to the rock-phosphate amended soil in two field experiments during 2013/2014 and 2014/2015 winter seasons. Interaction effects between those biofertilizers and foliar spraying with Saccharomyces cerevisiae extract on some microbial activities, growth characteristics as well as yield component of wheat were studied. Significant positive effects were obtained of phosphatase and available phosphorous content in rhizosphere of wheat after inoculation with Ps. fluorescens. Also, dual inoculation of Ps. fluorescenswith AM in presence of rock phosphate gave maximum values of phosphatase, mycorrhizal infection percentage and available P in wheat rhizosphere in both seasons especially when foliar spraying with yeast extract was applied. Meanwhile, application of both dual inoculants either alone or with yeast extract spraying led to considerable improvement in growth characteristics, photosynthetic pigments as well as biochemical composition of wheat plants when compared with untreated ones. Also, dual inoculation with Ps. fluorescensand AM increased gibberellins, auxins and cytockinins content either in the presence or absence of yeast spraying. Similar positive trend was observed in yield and yield component with good quality of chemical composition of wheat grains especially when dual inoculation combined with yeast foliar spraying were applied. The obtained results confirm the positive influence of co-inoculation with phosphate-solubilizing microorganisms in presence of rock phosphate as an active tool to improve wheat yield, also, support the role of Saccharomyces cerevisiae extract for enhancing biofertilization performance.
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