[Screening of wild barley genotypes with high phosphorus use efficiency and their rhizosphere soil inorganic phosphorus fractions].

A pot experiment was conducted to investigate the differences of 16 wild barley genotypes in phosphorus (P) uptake and use efficiency under the same P supply levels and the characteristics of inorganic P fractions in rhizosphere and non-rhizosphere soils of high P use efficiency genotypes. There existed greater differences in the P use efficiency for dry matter production at jointing stage (CV = 11.6%) and flowering stage (CV = 12.4%), and in the P use efficiency for grain yield at maturing stage (CV = 13.7%) among the genotypes. The biomass, P accumulation amount, and P use efficiency for dry matter production of high P use efficiency genotypes (IS-22-30 and IS-22-25) were significantly higher than those of low P use efficiency genotype (IS-07-07), and the grain yield of IS-22-30 and IS-22-25 was 3.10 and 3.20 times of that of IS-07-07, respectively. When supplied 0 and 30 mg x P kg(-1), the concentrations of available P and water soluble P in rhizosphere soils were significantly lower than those in non-rhizosphere soils, especially for the water soluble P. The concentrations of inorganic P fractions in the rhizosphere and non-rhizosphere soils were in the order of Ca10-P > O-P > Fe-P > Al-P > Ca2-P > Ca8-P. When supplied 30 mg x P kg(-1), the Ca8-P concentration in high P use efficiency genotypes rhizosphere soils at jointing and flowering stages was significantly lower than that in low P use efficiency genotype rhizosphere soil, but the Ca2-P concentration was in adverse. When no P was supplied, the concentrations of Ca2-P and Ca8-P in high P use efficiency genotypes rhizosphere soils were significantly higher than those in low P use efficiency genotype rhizosphere soil, and the Ca10-P concentration in the rhizosphere soils of all genotypes decreased. When supplied 30 mg x P kg(-1), the Fe-P and O-P concentrations in high P use efficiency genotypes rhizosphere soils were significantly higher than that in low P use efficiency genotype rhizosphere soil, but the Al-P concentration presented an opposite trend. Under no P supply, the Al-P, Fe-P, and O-P concentrations in high P use efficiency genotypes rhizosphere soils were significantly lower than those in low P use efficiency genotype rhizosphere soil. It was suggested that under low P stress, the capabilities of high P use efficiency genotypes in activating and absorbing soil A1-P and Ca2-P were stronger than those of low P use efficiency genotype.