Abstract: 【Objective】The objective of this study is to explore the ability to uptake phytate-Po in P-efficient wild barley genotypes, analyze the variance in plant growth, P absorption and characteristics in rhizosphere soil, and to provide a theoretical basis for revealing the mechanism of Po utilization on P-efficient genotypes wild barley under low available P stress.【Method】P-efficient genotypes (IS-22-30 and IS-22-25) and the P-inefficient genotypes (IS-07-07) were identified by screening the genetic stocks of wild barley. They were grown in low P soil supplied Na-phytate in a pot experiment. The experiment consisted of three different Po fertilizer application treatments, including no Po (CK), 15 mg·kg^-1 (Po15) and 30 mg·kg^-1 (Po30) in soil. The biomass production, P accumulation, acid phosphatase and phytase activities at root and rhizosphere, and organic phosphorus fractions in rhizosphere of different P efficiencies wild barley at jointing stage under different phytate-Po levels were measured. 【Result】The biomass production and P accumulation of different P efficiencies wild barley were significantly increased, while root/shoot ratio had a decreasing tendency by supplying phytate-Po. The biomass, P accumulation and root/shoot ratio of P-efficient genotypes were higher than those of P-inefficient genotype. In addition, the rate of increase in biomass and P accumulation of P-efficient genotypes was higher than that of P-inefficient genotype by supplying phytate-Po. Acid phosphatase and phytase activities in root were promoted in wild barley with decreasing of phytate-Po concentration. Acid phosphatase and phytase activities in root of P-efficient genotypes were observably higher by 1.15-1.24 times and 1.18-1.34 times than those of P-inefficient genotype, respectively. Acid phosphatase and phytase activities in the rhizosphere soil were higher than that of non-rhizosphere soils, and the enzyme activities increased significantly with the increasing concentration of phytate-Po. Furthermore, the enzyme activities in the rhizosphere soil of P-efficient genotypes were 1.23-1.33 times and 1.15-1.30 times than those of P-inefficient genotype under all Po levels. The concentration of organic phosphorus fractions in rhizosphere and non-rhizosphere soils of wild barley were increased by supplying Po. The labile organic phosphorus and moderate labile organic phosphorus of P-efficient genotypes were observably lower than those of P-inefficient genotype. However, for moderate resistant organic phosphorus and resistant organic phosphorus, there was no significant difference among different P efficiencies genotypes. The results showed that the concentrations of organic phosphorus fractions in rhizosphere soils were higher than those of non-rhizosphere soils due to the depletion of organic phosphorus. The waning of labile organic phosphorus and moderate labile organic phosphorus in rhizosphere soils of P-efficient genotypes was found, and the amounts of deficiency were 0.64-1.12 mg·kg^-1 and 13.8-33.9 mg·kg^-1, respectively.【Conclusion】The biological availability of labile organic phosphorus and moderate labile organic phosphorus in rhizosphere soils of P-efficient wild barley genotypes was enhanced by more acid phosphatase and phytase for root or microorganism in rhizosphere microecology secreting. Thereby, P-efficient wild barley genotypes had superior ability to uptake and utilize Po, and could adapt to the soil environment in lack of available P.

Key words: wild barley, P-efficient, phytate-Po, P uptake, P accumulation