叶面施钙缓解花生低夜温及其恢复过程中光合障碍的机制

Photosynthesis, susceptible to temperature and plant nutrition, is the basis for plant growth and development. It has been found that photosynthetic performance of peanut was reduced dramatically by low night temperature stress and calcium foliar spray could alleviate the adverse effect of low night temperature stress. On the basis of existing research, we have artificial climate chamber to imitate low night temperature stress and its recovery process using the various chilling-sensitive peanuts screened as test material. And peanuts seedlings will be regulated by calcium and its inhibitors under low night temperature condition. Firstly, calcium regulation on response to low night temperature from stoma, chloroplast ultrastructure and calcium distribution of leaves will be cleared through biological electron microscopy and digital image analysis technique. Secondly, the gene expression of Rubisco and CaM in peanuts will be studied by real time fluorescent quantitative PCR to clear the calcium regulation on response of their genes expression to low night temperature stess. Thirdly, the chlorophyll fluorescence technique and biochemical methods combined with the short-term low night temperature experiment will be carried out to study the effects of calcium on the photosystem performance, photosynthate feedback inhibition-carbohydrates metabolism and translocation of peanut leaves under low night temperature. Finally, it will be shown to analyze the above results that the key improvement mechanism of calcium foliar spray on peanut photosynthesis under low night temperature stress and recovery, which may lay the theoretical foundation in application of calcium fertilizers to improve peanut cold resistance and extending agricultural production area.

光合作用是植物生长发育的基础，对温度和植物养分变化高度敏感。我们前期研究发现，低夜温显著降低花生光合性能，而叶面施钙可明显缓解低夜温造成的光合障碍。在已有研究基础上，以不同冷敏感型花生品种为试材，利用人工气候室模拟低夜温胁迫及其常温恢复过程，通过叶面施钙及钙抑制剂预处理花生苗，首先采用生物电子显微镜及数字图像分析技术，明确气孔、叶绿体超微结构和叶片钙素分布对低夜温响应的钙素调控规律；其次，采用qPCR技术，研究花生Rubisco、CaM基因表达情况，明确基因表达对低夜温胁迫的响应规律及钙的调控作用；最后，采用叶绿素荧光技术及生理生化方法，结合短时低夜温胁迫和特异性验证试验，研究钙对低夜温胁迫下花生光系统功能、光合反馈抑制物质（碳水化合物）代谢及运转的影响。最终结合以上结论，揭示钙缓解花生低夜温光合障碍的机制，这将为农业生产中利用施肥（如钙肥）来改善花生耐寒性和拓展其栽培区域奠定理论基础。

花生（Arachis hypogaea）是世界重要的油料和经济作物，在保障我国食用油安全方面具有举足轻重的作用。低温是限制花生地理分布和生产的主要环境因子之一，冷害普遍存在，尤其以北方高纬度区域、西南高海拔地区为甚。在北方春季的花生栽培中，低温冷害经常发生，严重降低花生产量和品质。前期研究发现，叶面施钙具有显著提高花生耐冷性的调控效果，但其中的作用机制尚不清楚。为此，深入探讨钙素营养缓解花生低温光合障碍的机制这一科学问题，将为农业生产中利用施肥（如钙肥）和植物逆境营养遗传育种等方式来改善花生耐寒能力和拓展其栽培区域奠定理论基础；同时这方面研究结果也可以指导花生栽培过程中钙素等养分管理及相应的新型肥料开发。.本文以冷敏感型花生品种“丰花一号”为试材，用前期试验已筛选出的适宜浓度钙离子及其抑制剂对花生低夜温光合障碍进行调控。我们研究发现，外源施钙预处理能够提高低夜温下花生对矿质元素的吸收和花生根、茎、叶干物质的积累；钙素主要通过提高冷胁迫下花生叶片的气孔导度，进而缓解冷胁迫导致的花生叶片光合速率的降低。钙素营养对花生低温光合膜损伤具有显著的修复作用，钙离子能够平衡PSII与PSI之间激发能的分配。外源钙离子显著解除花生PSII和PSI的光抑制。通过克隆与分析钙调蛋白与膜联蛋白的基因全长和基因表达特征，我们发现花生钙调蛋白和膜联蛋白作为钙肥（Ca2+）的受体，它在钙离子缓减冷胁迫限制花生光合作用的营养信号传导中起到重要作用。