Effects of phosphorus sources on phosphorus fractions in rhizosphere soil of wild barley genotypes with high phosphorus utilization efficiency

High P-efficiency( IS-22-30,IS-22-25) and low P-efficiency( IS-07-07) wild barley cultivars were chosen to evaluate characteristics of phosphorus uptake and utilization,and properties of phosphorus fractions in rhizosphere and non-rhizosphere in a pot experiment with 0( CK) and 30 mg P·kg- 1supplied as only Pi( KH2PO4),only Po( phytate) or Pi +Po( KH2PO4+ phytate).The results showed that dry matter and phosphorus accumulation of wild barley in the different treatments was ranked as Pi Pi + Po Po CK. In addition,dry matter yield and phosphorus uptake of wild barley with high P-efficiency exhibited significantly greater than that with low P-efficiency.The concentration of soil available phosphorus was significantly different after application of different phosphorus sources,which was presented as Pi Pi + Po Po. The concentration of soil available phosphorus in high P-efficiency wild barley was significantly higher than that of low P-efficiency in the rhizosphere soil. There was a deficit in rhizosphere available phosphorus of high P-efficiency wild barley,especially in Pi and Pi + Po treatments. The inorganic phosphorus fractions increased with the increasing Pi treatment,and the concentrations of inorganic phosphorus fractions in soil were sorted as follows: Ca10-P O-P Fe-P Al-P Ca2-P Ca8-P. The contents of Ca2-P and Ca8-P for high P-efficiency wild barley showed deficits in rhizosphere soil under each phosphorus source treatment. In addition,enrichment of Al-P and Fe-P was observed in Pi treatment in rhizosphere soil. The concentrations of organic phosphorus fractions in soil were sorted as follows:moderate labile organic phosphorus moderate resistant,resistant organic phosphorus labile organic phosphorus. The labile and moderate labile organic phosphorus enriched in rhizosphere soil and the greatest enrichment appeared in Pi treatment. Furthermore,the concentrations of moderate resistant organic phosphorus and resistant organic phosphorus decreased in rhizosphere soil. The concentrations of labile and moderate labile organic phosphorus in rhizosphere soil of high P-efficiency wild barley were significantly higher than that of low P-efficiency wild barley in each phosphorus source treatment. However,moderate resistant organic phosphorus and resistant organic phosphorus concentrations had no significant difference between the two genotypes. Wild barley with high P-efficiency demonstrated a greater ability of mobilization and uptake Ca2-P,Ca8-P,Al-P and labile organic phosphorus than that with low P-efficiency under Pideficiency.