甘薯块根生长过程中促进光合产物卸载的机制与途径

Source:sink imbalance was one of the major factors restricting the high and steady yield of sweet potato. The root cause of source:sink imbalance was unsmooth transportation of photosynthate. And photosynthate transportation between source and sink had close relations with unloading capacity of photosynthate in storage roots. But the study of mechanism and culture measure of photosynthate unloading in storage roots was relatively weak until now. This study chose sweet potato varieties with significantly different sink-source characters as materials. The unloading pathway of photosynthate in storage roots was made clear mainly by ways of fluorescent labeling, electron microscopic methods and physiological detection first. And then the genetic diversity and mechanism of photosynthate unloading in storage roots were studied under different genetic background, the regulation mechanism of culture measure on photosynthate unloading in storage roots was studied as well. Meanwhile highly effective cultivation methods was sought to promote photosynthate transportation from source to sink and increase storage roots yield. The result of this study had an important theory and practice meaning in finding regulation mechanism and cultivation methods of promoting photosynthate transportation from source to sink.

源库失调是制约甘薯高产稳产的主要因素。光合产物运转不畅是甘薯源库失调的根本原因。源库间光合产物的运转与库端卸载能力有密切关系。关于甘薯库端光合产物的卸载机制及栽培技术调控，迄今认识较为薄弱。 本项目在采用荧光标记、电镜观察和生理检测等方法确定甘薯块根中碳水化合物卸载途径的基础上，选择源库特征差异显著的不同甘薯品种为材料，研究不同遗传背景条件下库端光合产物卸载的遗传差异与机制；栽培技术措施对库端光合产物卸载的调控机制；探索促进甘薯源库间光合产物运转、提高块根产量的栽培途径。研究结果对阐明促进甘薯源库间光合产物运转的调控机制具有重要的理论意义，对明确促进甘薯源库间光合产物运转、提高块根产量的栽培学途径具有重要的实践价值。

项目背景：源库失调是制约甘薯高产稳产的主要因素，光合产物运转不畅是甘薯源库失调的根本原因。源库间光合产物的运转与库端卸载能力有密切关系。关于促进甘薯库（块根）光合产物卸载的机制与途径，迄今认识较为薄弱。. 主要研究内容：（1）不同产量水平甘薯品种光合产物分配差异及其主要原因。（2）确定甘薯块根中光合产物的卸载路径，研究高产和低产甘薯品种库（块根）光合产物卸载机制的差异。（3）研究氮钾营养调控甘薯块根形成或块根生长过程中光合产物运转和库端卸载的机制、及与块根产量的关系。（4）研究土壤紧实度调控甘薯光合产物运转的生态和生理原因。. 重要结果和关键数据：与低产甘薯品种相比，高产品种光合产物由叶片向块根转运效率高的主要原因是库端卸载能力强。块根从形成到膨大过程中，库端光合产物的卸载途径存在质外体途径-共质体途径的转变过程，在块根膨大过程中，光合产物的卸载以共质体途径为主。高产品种库端光合产物卸载能力较强的生理机制是：块根膨大前期，淀粉合成早、效率高，卸载到块根中的蔗糖转化顺畅；块根膨大前、中期，可溶性酸性转化酶活性较高，蔗糖区隔到液泡的能力强，保证了胞质内外较高的蔗糖浓度梯度。钾素营养促进光合产物由地上部向块根运转的主要原因是促进了块根中蔗糖向淀粉的转化、提高了胞质内外蔗糖浓度梯度，有利于蔗糖在块根中的卸载。施用适量铵态氮肥作为基肥可以促进甘薯块根早形成，有利于牵制中后期地上部生长、促进光合产物向块根运转。耕作层土壤中氮钾比例（N/K）为0.5左右时，有利于块根膨大和产量形成。改善土壤通气性促进甘薯光合产物运转的生态原因是提高了块根形成期耕作层土壤的温度日较差；生理原因是提高了块根膨大期干物质积累初始势，促进了块根膨大过程中淀粉的合成与积累。. 科学意义：本项目成果对于促进甘薯高产栽培理论发展、寻找提高光合产物运转效率的技术途径，具有比较重要的理论意义和应用价值。