Abstract: Low phosphorus (P) stress is one of the constraints on crop growth and yield. ‘Macrotyloma uniflorum (Lam.) Verdc. Yazhou’ is a high-quality forage for livestock,but its response mechanisms on low P availability are largely unknown. In this study,in order to investigate the effects of low P stress on the growth and physiological characteristics of M.uniflorum,plant growth,P concentration and acid phosphatase (ACP) activity of M.uniflorum under different P treatments (5 μM,100 μM and 250 μM KH₂PO₄) were analyzed in hydroponic conditions. Results showed that plant height,number of trifoliate leaf,leaf area,total root length,root surface area,root volume and, plant dry weight of M. uniflorum were significantly inhibited by 5 μM P treatment compared to 100 μM and 250 μM P treatments. In addition,5 μM P treatment significantly reduced P content,soluble P content and cell wall P content. However,increasing in the total ACP and cell wall ACP activities in leaves and roots was observed under 5 μM P condition compared to 100 μM and 250 μM P treatments. The total ACP activities in leaves and roots of M. uniflorum under 5 μM P treatment was 1.5~1.6 times higher than those under 250 μM P treatment,respectively. Furthermore,cell wall ACP activity in leaves and roots was 1.2~1.3 times higher than those under 250 μM P treatment,respectively. The results suggest that M. uniflorum could induce more acid phosphatase in response to P deficiency,thereby increasing P utilization.

Key words: Macrotyloma uniflorum, Low P stress, Acid phosphatase, P content

摘要： 本试验为探究硬皮豆（Macrotyloma uniflorum）对低磷胁迫的响应机制，以‘崖州硬皮豆’为材料，采用水培方法，分析了不同磷浓度（5 μM，100 μM和250 μM KH₂PO₄）处理对硬皮豆生长和生理特性的影响。结果表明：与100 μM和250 μM磷处理相比，5 μM低磷处理抑制了硬皮豆株高、复叶数、叶面积、总根长，根表面积和根体积以及植株干重。同时，5 μM磷处理显著降低了地上部和根部磷含量、降低了叶片和根系可溶性磷含量和细胞壁磷含量；与100 μM和250 μM磷处理相比，5 μM磷处理增加了叶片和根系总酸性磷酸酶（Acid phosphatase，ACP）活性和细胞壁ACP活性；5 μM磷处理下叶片和根系总ACP活性是250 μM磷条件下的1.5~1.6倍，而叶片和根系细胞壁ACP活性是250 μM磷条件下的1.2~1.3倍。因此，提高酸性磷酸酶活性可能是硬皮豆响应低磷胁迫的重要机制。

关键词: 硬皮豆, 低磷胁迫, 酸性磷酸酶, 磷含量