施钾是冬油菜生产中重要的栽培措施，它能促进油菜的生长，增加角果数和每角粒数，这与施钾改善油菜的光合作用紧密联系。钾对作物光合作用的影响已有广泛的研究，但研究中往往关注某个限制因子是造成光合速率降低的主因，而忽视钾素浓度的变化对这个过程的影响。叶片和角果皮作为油菜主要的光合器官，其结构和功能存在明显差异，而钾对它们光合作用的影响及机制并不明晰。本研究通过田间监测明确施钾对油菜主要光合器官演替规律的影响，结合形态特征、光合能力以及光合代谢产物的分析，阐明油菜叶片和角果皮光合特性的差异及其对钾素营养的响应；进一步量化作物钾素浓度和光合作用各限制因子（气孔导度、叶肉导度和生化因子）的关系，确定不同钾素胁迫下油菜光合作用的主要限制因子，利用电镜、荧光探针等技术揭示各限制因子影响光合作用的机制，最终建立基于光合作用变化的临界钾素浓度阈值，为合理施用钾肥，充分挖掘油菜生产潜力提供理论和技术支撑

Potassium (K) fertilization is one of the most indispensable cultivations of winter oilseed rape production. It can promote crop growth, increase the numbers of pods per plant and seeds per pod, which is closely related to the improvement of photosynthesis due to K fertilization. Many studies about the effects of K fertilizer on photosynthesis have been conducted, nevertheless, the studies focus on the major limiting factors of crop photosynthesis and the changes of K concentration on this process are usually neglected. Furthermore, both leaf and pod wall are the dominant photosynthetic organs; their structures and functions are quite different. But the influences and mechanisms of K fertilization on the photosynthesis characteristics of leaf and pod wall of oilseed rape are unclear. Therefore, the succession patterns of these photosynthetic organs and their responses to K fertilization are ascertained through the field experiments. With the combination of the analysis of morphology characteristics, photosynthetic capacity and metabonomics, the influences of K fertilization on the photosynthetic characterizes of leaf and pod wall are clarified. Moreover, the correlations between crop K concentration and the limiting factors of photosynthesis (stomatal, mesophyll conductance and biochemical limitations) are quantified to determine the principal limitations of oilseed rape photosynthesis under different K stress. Then the mechanisms of K fertilization on photosynthesis are revealed depending on the modern technologies including the electron microscope, the fluorescent probes etc. Finally, the critical K concentrations based on the crop photosynthesis characteristics are established. This will provide the theoretical basis and technical support of optimizing K fertilization and expanding the potential yield of oilseed rape.