水稻通气组织形成对氮素和水分吸收能力的影响及其机理研究

Hydroponic and pot experiments supplied with different nitrogen forms and water stress (Hydroponic experiments simulated with 10% PEG 6000) should be conducted to investigate the effects of aerenchyma formation on rice nitrogen and water uptake. Under different treatments, we mainly plan to analyze the internal connection among water absorption and transport and characteristics of nitrogen nutrition in the whole plants, photosynthetic characteristics in the leaves, and aquaporin in the root systems. In addition, we will study the effects of aerenchyma formation on water absorption and transport in rice plants and aquaporin activity in roots under the different treatments . Also, we will discuss the relationship among water absorption and transport in roots, morphology structure of the root systems, water use in shoot, and drought resistance in the whole rice plants by different nitrogen forms. To clarify the mechanism of aerenchyma development influence on root nitrogen and water uptake.as a result,the biochemical or physiological process and its influencing factors will be revealed in the interrelationship between nitrogen nutrition and water as well as drought resistance, which can carve out a new way to research water use and drought resistance for plants, illustrate the internal mechanism on the growth of rice advanced by appropriate ammonium nitrogen in the production of water-saving irrigation, and provied varietal reference for conductions in different region with rice water-saving cultivation.

通过溶液培养以及聚乙二醇6000（PEG6000）处理模拟干旱的方法来研究不同形态氮素营养和水分条件下通气组织形成对水稻氮素和水分吸收的影响。分析不同处理下水稻水分吸收和运输、氮素营养特性、叶片光合特性以及根系水通道蛋白活性之间的内在联系，研究不同处理下通气组织的形成对水稻水分吸收和运输和根系水通道蛋白活性影响，探讨不同氮素营养调节水稻根系形态结构、根系水分吸收与运输、地上部水分利用以及水稻整体抗旱性的关系。阐明根系通气组织形成对水稻根系氮素和水分吸收的影响机理，揭示植物氮素营养与水分关系和抗旱性之间相互联系的生理生化过程及其影响因素。本项目不仅为研究水稻水分利用与抗旱性开拓新的思路，也有助于揭示水稻节水灌溉中维持土壤中相应比例的铵态氮营养促进水稻生长的内在机制，为水稻节水栽培提供一定的理论基础和品种参考。

为研究水稻根系通气组织形成对氮素和水分吸收能力的影响及其生理机制，采用营养液培养，利用聚乙二醇模拟水分胁迫的方法，研究了不同形态氮素和水分条件下根系通气组织形成对水稻氮素和水分吸收的影响。结果表明，（1）水分胁迫促进硝态氮营养水稻根系通气组织的形成，对铵态氮营养水稻根系通气组织无明显影响。与铵态氮营养水稻根系相比，水分胁迫促进了硝态氮营养水稻根系长度的变化，对根系数量的增加无显著影响。（2）与供铵态氮营养水稻相比，模拟水分胁迫条件下供硝态氮营养水稻根系乙烯释放量大，根系呼吸速率显著增加，活性氧清除酶( SOD、CAT和POD) 活性下降是导致硝营养水稻根系通气组织显著增大的主要原因。（3) 在两种水分条件下，铵态氮营养水稻的净光合速率和叶片渗透势均显著高于硝营养水稻。水分胁迫后，铵态氮营养的水稻新完全展开叶的叶绿素a、b含量均明显高于硝营养处理。铵营养水稻能够维持较高的光合特性，为水稻的生长提供更多的同化产物。（4）水分胁迫条件下，硝营养水稻硝酸还原酶显著降低，铵营养水稻基本不受水分胁迫影响。与正常条件下相比，水分胁迫条件下，硝营养水稻叶片对硝态氮的同化能力显著下降，铵营养水稻各部位对氮素的同化能力基本不受影响，从而保证了逆境下植物生长所需的充足氮源。（5）正常水分条件下，铵、硝营养水稻根系的水分吸收主要以细胞-细胞为主的共质体途径，水分胁迫后硝营养水稻根系水分吸收以质外体途径为主。因此，在干旱胁迫下，供应硝态氮营养的水稻根系通气组织的形成显著抑制了水分的吸收和运输。