【目的】有机磷为土壤磷库的重要组成部分，研究不同磷效率作物对有机磷的利用能力的差异，有助于了解作物高效吸收磷的机理。【方法】以磷高效基因型大麦(IS-22-25、IS-22-30)和低效基因型大麦(IS-07-07)为试验材料，植酸钠为有机磷源进行水培试验。设置5个植酸钠浓度(0.1、0.2、0.3、0.4、0.5 mmol/L)，使用根系扫描仪分析其根长、根表面积、根体积等形态特征，并测定根系与根系分泌的酸性磷酸酶、植酸酶活性等生理特征。【结果】随有机磷浓度降低，磷高效基因型野生大麦总根长、总表面积和总体积呈增加趋势。低有机磷浓度下，磷高效基因型大麦总根长较正常有机磷浓度(0.4 mmol/L)下增加了139.7%～146.0%，直径 D＜0.16 mm的根长提高了156.8%～161.5%，且磷高效基因型总根长较低效基因型高8.6%～60.4%。低有机磷浓度下，磷高效基因型根系各参数均显著高于低效基因型。随着有机磷浓度降低，磷高效基因型根总表面积提高了83.5%～117.5%，较低效基因型高14.0%～46.4%；根总体积提高了80.7%～119.3%，较低效基因型高19.6%～150.0%。随着有机磷浓度升高，磷高效基因型根系及其分泌酸性磷酸酶和植酸酶活性显著降低。低有机磷浓度下，磷高效基因型根系酸性磷酸酶和植酸酶活性增加了163.3%～172.2%和98.6%～121.2%，较低效基因型高14.4%～41.2%和23.1%～37.2%；磷高效基因型根系分泌酸性磷酸酶和植酸酶活性增加了157.8%～193.4%和172.4%～183.4%，较低效基因型高20.2%～45.7%和24.7%～51.4%。【结论】在低浓度有机磷胁迫下，磷高效基因型通过良好的根系形态，有效扩大了根系对水分和养分的接触空间，为磷高效基因型的快速生长和磷素吸收提供了条件；同时，低浓度有机磷胁迫增强了根系分泌酸性磷酸酶和植酸酶，提高了介质环境中磷素的生物有效性，对有机磷的吸收利用表现出明显优势。%[Objectives]Organic phosphorus (P) is an important component of soil P pools. Observing the response difference in root morphology of plants when exposured to low organic P stress will help understanding the mechanism of plant genotype P use efficiency in the environment.[Methods]A hydroponic experiment was conducted with P-efficient genotypes (IS-22-25 and IS-22-30) and P-inefficient genotype (IS-07-07) as test materials and with phytate sodium as organic P source. Five phytate-P levels were set up in the nutrition solution:0.1, 0.2, 0.3, 0.4 and 0.5 mmol/L. The root length, surface area and volume were analyzed using a root scanning system, and the activities of acid phosphatase and phytase were determined in roots of both wild barley genotypes.[Results]The total root length, surface area and volume in the P-efficient wild barley genotypes were increased gradually in response to the reduced organic P supply levels. In the low organic P level, the total root lengths in the P-efficient wild barley genotypes were increased by 139.7%–146.0% compared to those in the normal organic P condition (0.4 mmol/L), and the lengths were increased by 8.6%–60.4% in relative to that in the P-inefficient genotype. In the low organic P condition, the lengths of the roots (D<0.16 mm) in the P-efficient wild barley genotypes were 156.8%–161.5% higher than those in the normal organic P condition. Increases of 83.5%–117.5% and 80.7%–119.3% were observed in total surface area and total volume in the P-efficient wild barley in response to the reduction of organic P concentration, which were 14.0%–46.4% and 19.6%–150.0% higher than those in the P-inefficient wild barley, respectively. In addition, the activities of acid phosphatase and phytase were significantly reduced with the increasing levels of the organic P. In the low organic P condition, the activities of acid phosphoatase and phytase of the P-efficient wild barley were increased by 163.3%–172.2% and 98.6%–121.2%, which were 14.4%–41.2% and 23.1%–37.2% higher than those in the P-inefficient genotype, respectively. Meanwhile, the activities of acid phosphatase and phytase excreted by root in the P-efficient genotypes were increased by 157.8%–193.4% and 172.4%–183.4%, which were 20.2%–15.7% and 24.7%–51.4% higher than those in the P-inefficient genotype, respectively.[Conclusion]In the low organic P supply levels, good root morphology in the P-efficient wild barley genotypes was beneficial to expand attaching space of water and nutrition, which provided a good basis for growth and P uptake. Meanwhile, the increases in the activities of acid phosphatase and phytase excreted by roots in the P-efficient genotypes in the low organic P condition improved the bioavailability of P and accelerated to assimilate and utilize organic P, which should be one of the mechanisms contributing to efficiently absorb and utilize P in the P-efficient wild barley genotypes.
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