荧光硅量子点作为叶面光肥提高生菜对光能利用率的机理研究

采用水热法制备了荧光硅量子点。通过透射电镜、红外光谱、X射线光电子能谱、光致激发和发射光谱及荧光衰减曲线等手段对样品形貌及发光性能进行了研究。通过生菜种植实验,研究了荧光硅量子点作为叶面光肥提高生菜对光能利用效率的效应。实验结果表明,透射电镜测得所制备的荧光硅量子点尺寸均一,平均尺寸为3.6 nm。傅里叶红外变换光谱及X射线光电子能谱表明该量子点表面具有丰富的含氧官能团,因而具有优异分水散性。光致荧光光谱表明,该量子点的最佳激发和发射峰位分别为385 nm和450 nm,且不具备激发波长依赖特性。荧光硅量子点与生菜的离体叶绿体复合后发现,荧光强度下降但激发态寿命基本不变,同时,复合物对2,6-二氯酚靛酚的还原速率提高。以上结果表明,荧光硅量子点与叶绿体复合时产生了内滤效应,生菜的叶绿体吸收了硅量子点发射的蓝光用于光合作用,从而使生菜的干鲜重均得到了显著性提高。通过叶绿素荧光成像实验进一步验证了喷施荧光硅量子点叶面光肥时生菜的光合作用速率得到了提高。

Mechanism of Fluorescent Silicon Quantum Dot as Foliar Light Fertilizer to Improve Lettuce's Utilization of Light Energy

Fluorescent silicon quantum dots(SiQDs)were prepared by hydrothermal reaction method.The morphology and fluorescence properties of SiQDs were investigated by transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),photoluminescence(PL)excitation and emission spectra and excited-state decay curve.By lettuce cultivation experiment,the effect of SiQDs as foliar light fertilizer to improve light energy utilization of lettuce was studied.TEM image showed that the average size of the SiQDs is 3.6 nm with the uniform size.These results of FTIR and XPS demonstrated abundant oxygen-containing functional groups on SiQDs surface,which contributed to its excellent water dispersibility.The PL spectrum of SiQDs demonstrated that the optimal emission of the SiQDs is 450 nm when excited at 385 nm,which is also independent of excitation wavelength.When combined with chloroplast(CLP)in vitro,the PL intensity of the SiQDs decreased,but the PL lifetime did not change significantly.Furthermore,reduction rate of 2,6-dichlorophenolindophenol(DCPIP)in this combined system was increased.All these results above reveal that inner-filtration effect happens in SiQDs/CLP combined system.CLP can absorb the blue light emitted from SiQDs for photosynthesis to increase the total yield of fresh and dry weight of lettuce significantly.The chlorophyll fluorescence imaging results further demonstrated the increased maximum photosynthetic rate.