Effect of Microbial Inoculation on the Phosphorus acquisition Efficiency (PACE) of Corn and Sunflower

In order to investigate the effect of microbial inoculation on phosphorus acquisition efficiency of sunflower and corn, a glasshouse factorial experiment conducted in completely randomized block design with two plants (corn and sunflower) and five phosphorus (P) treatments including rock phosphate (RP), RP inoculated with the fungi solubilizing phosphate (RP), RP inoculated with the phosphate solubilizing bacteria (RP), RP with phosphate solubilizing bacteria and fungi (RP) and soluble P (PS) in three replications. After 9 weeks, plants were harvested and shoot dry weight (SDW) and P concentration (PC) were measured and then PE indices were calculated. The results showed that, there were significant differences in shoot dry weight (SDW), P concentration (PC) and plant total P (TP), P acquisition efficiency (PACE) and P utilization efficiency (PUTE) between microbial treatments and plant types. The fungi inoculation was more effective than other microbial treatments and on average, SDW increased from 7.3 g to 15.5 and PACE from 0.16 to 0.64. The single inoculation of phosphate solubilizing microorganisms increased the P efficiency indices significantly, but the con-inoculation of phosphate solubilizing had no significant effect on PE. Thus, according to the results the application of phosphate rock with phosphate solubilizing microorganisms can be recommended to minimize the costs of plant production and to reduce environmental problems.