水稻根际铵离子对钾离子跨细胞膜转运的调控及其与氮利用效率的关系

The balance between N and K uptake plays an important role on rice growth and yield formation. In submerged paddy field, ammonium was the main form of nitrogen in upper soil and solution in paddy field. In this project, in order to study the interaction between NH4+ and K+ in nutrient absorption and its relationship with nitrogen use efficiency, a high-NUE (Qilishimiao ) and a low-NUE (Huke 3) rice cultivar will be used as materials in hydroponic experiments and field trials. In hydroponic experiments, effects of ammonium on potassium uptake and their genotypic difference will be studied by analysis high and low affinity transport system for potassium under with or without ammomium, and transmembrane ammonium and potassium fluxes in the root meristem and elongation zones under varying ammonium concentrations. In field trials, varying nitrogen fertilizer amount will applied to paddy field with different potassium content, and plant morphology, photosynthesis, dry matter accumulation, yield formation, nitrogen and potassium uptake and use efficiency will be compared under with and without potassium fertilizer, and the relationship between nitrogen use efficiency and potassium absorption will be further analyzed. The results of the project will provide helpful knowledge to clarify the process of nitrogen absorption, reveal the mechanism of nitrogen use efficiency among varieties and environment, as well as to provide new theoretical foundation and guide way to nitrogen fertilizer application in rice production.

K、N养分平衡对水稻的生长发育和产量形成起着重要作用。水田淹水条件下，稻田上层土壤和溶液中以铵态氮为主，为探明水稻根际铵离子和钾离子吸收的交互作用及其与氮利用效率的关系，本项目以氮利用效率差异的常规中籼稻品种齐粒丝苗和沪科3号为材料，进行不同铵、钾浓度的水培试验和大田试验。通过水培试验分析铵离子对根系钾离子转运系统的影响，比较不同铵浓度下根系分生区和伸长区铵离子和钾离子流通微动态，探明铵对根系钾离子跨细胞膜运输的影响及品种间差异。通过在不同含钾量田块中进行氮肥试验，比较增施K肥后植株形态、光合生理、物质积累、产量形成、N和K吸收、氮肥和钾肥利用效率变化，探明水稻氮利用效率与钾吸收的关系。进而揭示水稻根际铵离子对钾离子跨细胞膜转运的调控及其与氮利用效率的关系。研究结果，有助于揭示品种间、环境间氮肥利用差异的机理，深化水稻氮肥吸收理论，为水稻氮肥施用技术的优化提供依据。

K、N养分平衡对水稻的生长发育和产量形成起着重要作用。水田淹水条件下，稻田上层土壤和溶液中以铵态氮为主，为探明水稻根际NH4+、K+吸收的交互作用及其与氮利用效率的关系，本项目以氮利用效率差异的常规中籼稻品种齐粒丝苗（QL）和沪科3号(HK)为材料，进行不同NH4+和K+浓度的水培试验和大田试验。通过水培试验分析NH4+对根系K+转运系统的影响，比较不同NH4+浓度下根系分生区和伸长区NH4+和K+流通微动态，发现NH4+抑制水稻苗期根系K+的高亲和转运和低亲和转运，NH4+对K+高亲和吸收的影响主要是由于铵竞争细胞膜上的钾载体所致；NH4+对K+吸收的抑制作用存在品种间差异，N低效的水稻品种HK在高NH4+下K+的吸收速率的降幅明显高于N高效水稻品种QL。通过在不同含钾量田块中进行氮肥试验，比较增施K肥后植株形态、光合生理、物质积累、产量形成、N和K吸收、氮肥和钾肥利用效率变化，发现高N肥下增施K肥，提高了植株生长时期的多项生理指标，如分蘖数、叶面积指数、干物重等；增施K肥后，QL、HK3 的N肥农学利用率分别提高了91.1%、103.3%。说明N肥下增K可促进植株生长，减少了高NH4+毒害作用，并提高了N肥利用效率，对N低效品种作用尤其明显。研究结果，有助于揭示品种间、环境间氮肥利用差异的机理，深化水稻氮肥吸收理论，为水稻氮肥施用技术的优化提供依据。