ROLE OF PHOSPHORUS SOLUBILIZING MICROORGANISMS IN THE GROWTH OF DATE PALM TREES

Date palm trees (Phoenix dactylifera) tolerate relatively harsh climatic and soil conditions in the UAE and gulf countries. The use of biofertilizers and organic manure to increase the efficiency of phosphorus uptake has been studied. Mycorrhiza fungi and Bacillus megatherum bacteria are used separately or in combination to study their role in phosphorus solubilization.
Soil phosphorus is the least mobile element in plants and soil contrary to other macronutrients. A large amount of phosphorus applied as fertilizer enters into the immobile pools through precipitation reaction with highly reactive Al³⁺ and Fe³⁺ in acidic, and Ca²⁺ in calcareous or normal soils.
Soil microorganisms play a key role in soil phosphorus dynamics and subsequent availability of phosphate to plants. Phosphorus solubilizing organisms play a role in phosphorus nutrition by enhancing its availability to plants through release from inorganic and organic soil phosphorus pools by solubilization and mineralization.
The principal mechanism in soil for mineral phosphate solubilization is lowering of the soil pH by microbial production of organic acids and mineralization of organic phosphorus by acid phosphatises. Use of phosphorus solubilizing organisms as inoculants increases phosphorus uptake. These microorganisms also increase prospects of using phosphatic rocks in crop production.
Greater efficiency of phosphorus solubilizing bacteria has been shown through co-inoculation with beneficial bacteria and mycorrhiza.