| Phosphorus (P) was one of limited macronutrient nutrient for crop production. The research subject needed to be solved in agriculture is improving crop P efficiency background of the lack of phosphate rock and low utilization of P fertilizer. Starting with P nutrition of crops, Study on the P dynamic transformation of crop rhizosphere soil, plasticity variety of root under P stress, P transport and re-utilization in crop which were beneficial to utilization of soil P pools by crop and improving utilization of P fertilizer.In this research, The purpose of this article was to reveals the mechanism of P efficient absorption and utilization through analyzing characteristics of rhizosphere soil inorganic P fractions, morphological and physiological characteristics of root, characteristics of leaves P fractions and acid phosphatase activity used different genotypes through pot experiment. The main results were as follows:(1) The concentrations of available P in rhizosphere soils was significantly lower than non-rhizosphere soils. Deficit amount of available phosphorus in P efficient barley genotypes DH110+、DH147 (32.2%-44.5%) was higher than P inefficient genotype (17.4%-28.1%) supplied with 25 (lower phosphorus),50 (low phosphorus) and 75 mg kg-1(normal phosphorus) phosphorus (P2O5). Ca2-P, Ca8-P and Al-P in rhizosphere soils of P-efficient barley genotypes showed deficit much more than the P inefficient genotype under low and lower P apply level, but they had no significant genotypic difference under P sufficient apply level. Fe-P in rhizosphere soils showed significant deficit only in the P inefficient genotype under lower phosphorus levels, which were 6.2%-6.3% lower than that in non-rhizosphere soil. Ca10-P and O-P had no significant genotypic difference under all P apply levels. The results showed that P efficient genotype barleys had strong ability of using Ca2-P, Ca8-P and Al-P, and non-labile Fe-P could been also exploited by P inefficient genotype barley.(2) The total root length, total root surface area, specific root length, lateral root length and surface area of P efficient genotype barley were 1.46-2.06,1.12-1.51,1.35-1.72, 1.69-2.42, and 1.40-1.78 times as much as that of those of P inefficient genotype barley, while the average root diameter was 70.6%-90.2% of P inefficient genotype barley, Adventitious root length and surface area had significant genotypic difference under P sufficient apply level. The contribution of total root length and total root surface area on P uptake of barley were much higher at different P apply levels, and the contribution of lateral root length and surface area on phosphorus uptake of barley increased significantly with decreasing P apply levels in soil, while the adventitious root length and surface area reduced. The results showed that P efficient genotype barley could better explore and uptake soil P enhanced lateral root growth. Root activity of P efficient genotype was higher than that in P inefficient genotype barley under different P apply levels, but Acid phosphatase activity was much lower in P inefficient genotype barley root under low P stress, indicated that P efficient genotype baley have greater ability to adapt low P stress.(3) The concentration of Pi in up and bottom leaves were markedly decreased under low P stress, but insoluble P did not. The concentration of nucleic P in up leaf of P efficient genotype barley significantly higher than that of P inefficient genotype barley under low P stress, but it showed opposite results in bottom leaf. The concentration and distribution ratio of ester P in bottom leaf of P efficient genotype barley lower than that in P inefficient genotype under low P stress, and the distribution ratio of ester P in bottom leaf (13.4%-17.0%) in P efficient genotype barley lower than that in up leaf (19.6%-21.3%) under lower P apply level, but it did not in P inefficient genotype barley. The concentration of ester P in up leaf significantly reduced in P inefficient genotype barley under low P stress, and it was significantly lower than that in P efficient genotype barley.The results indicated that P efficient genotype barley had better P nutrition in up leaf and more decomposition and transformation effects on soluble organic P in bottom leaf. In addition, P deficiency significantly enhanced the acid phosphatase activity in bottom leaf, and that in P efficient genotype barley was higher, the results also indicated that P efficient genotype barley had greater ability to reutilization of ester P in bottom leaf... |
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