纳米钼提高水稻硝态氮利用的生理机制

The utilization of nitrate in rice is closely related to nitrogen loss and nitrogen use efficiency in paddy soils. Molybdenum is an active component of nitrate reductase and plays a central role in nitrate reduction and nitrogen metabolism. In our previous studies, we have found that cubic nano-molybdenum could improve the utilization of nitrate and increase nitrogen use efficiency in rice compared with conventional molybdenum fertilizer. The physiological mechanism of nano-molybdenum to promote the utilization of nitrate in rice needs to be elucidated. In this project, different genetypes rice (Indica, Japonica, and Indica-Japonica hybrid rice) will be used as experimental materials. The nano-molybdenum prepared in the previous study will be the exogenous molybdenum. By setting different application levels of nano-molybdenum, the effects of nano-molybdenum on nitrate assimilation products and assimilation efficiency in different genetypes rice will be analyzed by using 15N isotope tracing technique and plant physiological and biochemical experiments. The differences in the effects of nano-molybdenum and sodium molybdate on the morphology, content and distribution of molybdenum in rice leaves will be studied by modern material analysis and testing techniques. With the assistant of enzyme inhibitor, the effects of nano-molybdenum and sodium molybdate on the enzymes activities of nitrate assimilation will be compared, and the key enzyme in nitrate assimilation promoted by nano-molybdenum will be clarified. Our research aims to explain the physiological mechanism for nano-molybdenum improving nitrate utilization in rice, providing theoretical basis for improving nitrate utilization efficiency and reducing nitrogen loss in paddy soils.

水稻对硝态氮的利用与稻田氮损失和氮素利用效率密切相关。钼是硝酸还原酶的重要组分，在硝态氮的还原和氮素代谢过程中具有核心作用。前期研究发现立方体纳米钼较常规钼肥更能促进水稻对硝态氮的利用，进而提高氮素利用效率，但纳米钼促进水稻硝态氮利用的生理机制尚待明确。本项目以不同水稻品种（籼稻、粳稻、籼粳杂交稻）为试验材料，以前期制备的纳米钼为外源钼，通过设置不同纳米钼施用水平处理，采用15N同位素示踪技术和植物生理生化实验方法，分析纳米钼对不同水稻品种硝态氮同化产物和同化效率的影响；采用现代材料分析测试技术，研究纳米钼与钼酸钠对水稻叶片中钼形态、含量及分布特征的影响；结合酶抑制剂处理，比较纳米钼和钼酸钠对硝态氮同化作用各个酶活性的影响，明确纳米钼通过促进何种酶活性来提高水稻硝态氮同化，揭示纳米钼促进水稻硝态氮同化的作用机制，以期为提高水稻硝态氮利用效率、减少稻田氮损失的新途径提供理论依据。

稻田土壤中的硝态氮是关系氮素损失和氮素利用效率的重要氮素形态，水稻对硝态氮的利用与稻田氮损失和氮素利用效率密切相关。钼是硝酸还原酶的活性组分，在植 物体内硝态氮的还原和氮素代谢过程中起着重要作用。前期研究发现纳米钼较常规钼肥更能促进水稻对硝态氮的利用，进而提高氮素利用效率，但纳米钼促进水稻硝态氮利用的生理机制尚待明确。本项目以南方优质食味粳稻为试验材料，以纳米钼为外源钼，通过设置不同纳米钼或钼氮配施水平处理，采用植物生理生化实验方法，分析了纳米钼对水稻硝态氮同化产物和同化效率的影响，发现在相同钼元素施用量下，纳米钼处理的水稻地上部氮素含量较钼酸钠处理高33.5%～44.0%，且差异均达显著水平；采用现代材料分析测试技术，研究了纳米钼与钼酸钠对水稻叶片中钼结合形态、含量及分布影响的差异，发现在相同钼施用水平下，离子钼处理的水稻根系较纳米钼处理具有更高的钼含量，但水稻地上部钼元素含量差异不显著，这表明纳米钼提高了钼元素在水稻中的运输和利用效率；结合酶抑制剂处理，比较了纳米钼和钼酸钠对硝态氮同化作用各个酶活性的影响，明确了纳米钼通过促进水稻硝酸还原酶、谷氨酸合成酶和谷氨酰胺合成酶的活性来提高水稻硝态氮同化，揭示了纳米钼促进水稻硝态氮同化的作用机制。本项目研究结果为利用新型纳米肥料提高水稻硝态氮利用效率、减少稻田氮损失的新途径提供了理论依据。