Contribution of Pseudomonas mendocina and Glomus intraradices to aggregate stabilization and promotion of biological fertility in rhizosphere soil of lettuce plants under field conditions

Abstract

A field-plot experiment was undertaken to compare the effect of inorganic fertilizer with that of inoculation with an arbuscular mycorrhizal fungus, Glomus intraradices, or with a plant-growth-promoting rhizobacterium, Pseudomonas mendocina, alone or in combination with inorganic fertilizer, on plant growth and nutrient uptake by lettuce. The influence of the microbial inoculation treatments on soil physical, biochemical and biological properties was also assessed. Two months after planting, fertilizer and inoculation with G. intraradices or P. mendocina had significantly increased shoot and root biomass and foliar nutrient contents (P, Fe). The inoculation with G. intraradices or P. mendocina both increased the soil water-soluble carbohydrates and the percentage of stable aggregates. In this study, we provide the first evidence of the beneficial effect of a plant-growth-promoting rhizobacterium on soil aggregate stabilization under field conditions. Only inoculation with P. mendocina had a significant effect on the dehydrogenase and phosphatase activities, 21 and 89%, respectively, compared with the control. Inorganic fertilization alone did not increase aggregate stability or enzyme activities in soil, even though this treatment produced the largest increases in mass of lettuce.

Effects of plant growth-promoting rhizobacterium (PGPR) and arbuscular mycorrhizal fungus (AMF) on antioxidant enzyme activities in salt-stressed bean (phaseolus vulgaris l.)

“…We have shown the beneficial effect of this PGPR strain on soil aggregate stabilisation (Kohler et al 2006). Previous studies have described a negative relationship between soil aggregation and percentage of Na + saturation in the ex-change complex (Lax et al 1994). In this context, the reduced Na + concentrations recorded in shoots of P. fluorescence-colonised plants could be due to the lower percentage of exchangeable Na + in the soil cultivated with such plants.…”

“…There are several reports of lower Na + concentrations in AM plants, compared with non-AM plants, under salinity (Giri & Mukerji 2004;Ashraf et al 2004;Sharifi et al 2007). In the case of P. fluorescence, this PGPR strain can produce exopolysaccharides that bind cations, including Na + (Kohler et al 2006), thus decreasing the content of Na + available for plant uptake. We have shown the beneficial effect of this PGPR strain on soil aggregate stabilisation (Kohler et al 2006).…”

“…In the case of P. fluorescence, this PGPR strain can produce exopolysaccharides that bind cations, including Na + (Kohler et al 2006), thus decreasing the content of Na + available for plant uptake. We have shown the beneficial effect of this PGPR strain on soil aggregate stabilisation (Kohler et al 2006). Previous studies have described a negative relationship between soil aggregation and percentage of Na + saturation in the ex-change complex (Lax et al 1994).…”

Effect of Zinc and Bio Fertilizers on Antioxidant Enzymes Activity, Chlorophyll Content, Soluble Sugars and Proline in Triticale Under Salinity Condition

“…PGPR can facilitate plant growth indirectly by reducing plant pathogens, or directly by facilitating the uptake of nutrients from the environment, by influencing phytohormone production (e.g. auxin, cytokinin and gibberellins) and production of siderophores (Kohler et al, 2006). Mycorrhiza is a symbiotic association between plant roots and fungi.…”

Synergistic Effects of Arbuscular Mycorrhizal Fungi and Plant Growth Promoting Rhizobacteria for Sustainable Agricultural Production

“…PGPR inoculation may help to improve crop resistance against abiotic stress conditions. EPS produced by P. mendocina (Kohler et al, 2006) bind to soil cations including Na and reduce the Na available for plant uptake. Glycoprotein (glomalin) produced by AMF can act as an insoluble glue to stabilize aggregates (Wright and Anderson, 2000).…”