Bacterial help with fertility and nutrient uptake
Another a biotic stress that plants face is obtaining adequate soil nutrients. Although soil fertilization is typically required for agricultural production, it can cause nitrate and phosphate accumulation that eventually contaminates surface and ground waters. Phosphate run-off is associated with eutrophication of surface waters, resulting in increased fish mortality [15]; in addition, nitrogen run off from US agriculture into the Mississippi River is linked to oxygen starvation in the Gulf of Mexico, creating ‘dead zones’ where shrimp and fish populations are greatly reduced [15]. These environmental impacts of fertilization can be attributed, in part, to low uptake efficiency by crops. For example, phosphorous is highly reactive with iron, aluminium and calcium in soils, which can result in precipitation of up to 90% of the soil phosphorus [16], thus making it largely unavailable to plants.
PGPR have promise as components in approaches for maintaining adequate plant nutrition and reducing the negative environmental effects of fertilizers. Plant growth promotion by some PGPR has been associated with the solubilization and increased uptake of phosphate [16].PGPR have also been reported to affect nitrate uptake byplants [17,18] .