低磷胁迫下大麦叶片磷素利用特征

以大麦(Hordeum vulgare)磷高效基因型(DH110和DH147)和低效基因型(DH49)为材料, 采用盆栽实验研究大麦在极低磷(25 mg·kg^-1土)、低磷(50 mg·kg^-1土)和正常磷(75 mg·kg^-1土)处理下叶片的磷组分和酸性磷酸酶活性特征。结果表明, 低磷胁迫显著降低大麦叶片的无机磷含量, 但对难溶态磷含量影响较小。高效基因型上部叶核酸态磷含量显著高于低效基因型, 而下部叶则显著低于低效基因型, 是低效基因型的18.4%-91.4%。大麦下部叶酯磷含量和分配比例表现为高效基因型低于低效基因型, 而上部叶仅在低效基因型中显著低于高效基因型。核酸态磷和酯磷在高效基因型叶片中的含量分配表明其上部叶的磷素营养状况较优, 而下部叶易溶性有机磷的分解转化作用更强。低磷和极低磷胁迫下, 下部叶酸性磷酸酶的活性显著增加, 且高效基因型显著高于低效基因型, 分别为低效基因型的1.29-1.41倍。磷高效基因型大麦通过提高下部叶酸性磷酸酶活性加强酯磷和核酸态磷的分解, 转化为无机磷, 增加可移动性磷源的含量和比例, 以提高生育后期大麦的磷素再利用能力。

Characterization of Phosphorus Utilization in Barley Leaf under Low Phosphorus Stress

To study the character of P fractions and acid phosphatase in leaf, we conducted a pot experiment of super-low P (25 mg·kg^-1 soil), low P (50 mg·kg^-1 soil) and normal P (75 mg·kg^-1 soil) in P-efficient barley (DH110, DH147) and P-inefficient barley (DH49). Inorganic P concentration was reduced significantly by low P stress, except for insoluble phosphate, in leaves of barley. The nucleic P concentration in upper leaves was higher in P-efficient than P-inefficient barley, but the nucleic P concentration in bottom leaves was lower; only 18.4% to 91.4% of that in P-inefficient barley. The ester P concentration and distribution ratio in bottom leaves was less in P-efficient than P-inefficient barley. However, the ester P concentration was decreased significantly only in P-inefficient barley and was significantly lower than in P-efficient barley. Moreover, the distribution of nucleic acid P and the ester P in P-efficient blades showed a better nutritional status of P in upper leaves and stronger decomposition conversion of soluble organic P in bottom leaves. Under P-deficiency, the acid phosphatase activity in bottom leaves increased significantly and was 1.29 to 1.41 times higher in P-efficient than P-inefficient barley. The P-efficient barley could improve inorganic P transformation from ester-P and nucleic P by enhancing the acid phosphatase activity of lower leaves, which increases the content and ratio of mobility P to improve P-recycling in the late growth stage of barley.