FTIR光谱结合曲线拟合研究萌发水稻种子

种子的萌发是种子生命历程中的主要组成部分之一，了解种子萌发过程中经历的生理生化变化，准确确定种子的活力，对农业生产很重要，因而，研究种子萌发有重要意义。采用傅里叶变换红外光谱结合曲线拟合研究不同萌发程度的水稻种子，以探寻种子贮藏物质动员情况，对不同萌发时间的水稻种子进行傅里叶变换红外光谱、二阶导数光谱、二维相关红外光谱和曲线拟合研究。结果显示，原始红外光谱整体相似，光谱反映出水稻种子的主要贮藏物质为淀粉、蛋白质和脂肪；吸收峰强度比A_{1 659}/A_{1 019}，A_{1 740}/A_{1 019}，A_{1 157}/A_{1 019}，A_{1 157}/A_{1 081}随萌发时间的增加而降低。814～1 000和1 028～1 340 cm-1范围内的二维相关红外光谱结果显示自动峰个数和最强自动峰的位置、强度随种子萌发时间的增加而变化，表明种子在萌发过程中糖类和蛋白质发生变化。二阶导数光谱在1 200～950 cm-1范围内出现七个峰，其中988 cm-1处的峰随萌发时间的增加向较高波数蓝移，而1 053和1 158 cm-1处的峰向较低波数红移，表明水稻种子在萌发过程中多糖的结构和含量可能发生了变化；在1 700～1 600 cm-1范围内出现九个峰，其中1 641和1 692 cm-1处的峰呈现随萌发时间的增加红移到较低波数的趋势，表明水稻种子在萌发过程中蛋白质的结构和含量可能发生了变化；在1 800～1 700 cm-1范围二阶导数光谱仅观察到1 712和1 744 cm-1处的两个峰，其中1 744 cm-1由脂类物质C═O伸缩振动引起，为脂肪的特征峰。为进一步研究水稻种子萌发过程中贮藏物质的具体变化，以二阶导数光谱确定的子峰位置和数目为依据，对原始红外光谱的1 200～950与1 800～1 600 cm-1区域进行曲线拟合分析。曲线拟合结果显示，随萌发时间的增加，多糖和蛋白质的相对含量总体上呈现下降趋势，脂肪的相对含量先降后升。研究表明，傅里叶变换红外光谱结合曲线拟合可作为研究种子萌发的有效手段。

Study of Germinated Rice Seeds by FTIR Spectroscopy Combined With Curve Fitting

Seed germination is one of the main components of the seed life course. Agricultural production needs to understand the physiological and biochemical changes in seed germination and accurately determine the vigor of seeds. Therefore, it is of great significance to study seed germination. In order to explore the mobilization of storage materials during seed germination, Fourier transforms infrared spectroscopy (FTIR) combined with curve fitting was used to study rice seeds with different germination days. The rice seeds with different germination times were studied by original infrared spectra, second derivative spectra, two-dimensional correlation infrared spectra and curve fitting. The results showed that the original infrared spectra were overall similar. The spectra reflected that the main storage substances of rice seeds were starch, protein and fat. The absorption peak intensity ratios of A_{1 659}/A_{1 019}, A_{1 740}/A_{1 019}, A_{1 157}/A_{1 019} and A_{1 157}/A_{1 081} decreased with germination time. The results of two-dimensional correlation infrared spectroscopy in the range of 814～1 000 and 1 028～1 340 cm-1 showed that the number of auto-peaks, and the position and intensity of the strongest auto-peaks changed with the increase of seed germination time, indicating that carbohydrate and protein changed during seed germination. The second derivative spectra showed seven peaks in the range of 1 200～950 cm-1. The 988 cm-1 peaks shifted to the higher wavenumber with the increase in germination time, while the peaks at 1 053 and 1 158 cm-1 were shifted to a lower wavenumber, which indicated that the structure and content of polysaccharides in rice seeds changed during germination. Nine peaks appeared in the range of 1 700～1 600 cm-1, among which the peaks at 1 641 and 1 692 cm-1 moved to lower wavenumber with the increase in germination time, indicating that the protein structure and content of rice seeds may have changed during germination. In the range of 1 800～1 700 cm-1, only two peaks at 1 712 and 1 744 cm-1. There are observed in the second derivative spectra, which 1 744 cm-1 is caused by the C═O stretching vibration of the lipid substance. In order to further explore the specific changes of storage substances during the germination of rice seeds, curve fitting analysis was carried out in the regions of 1 200～950 and 1 800～1 600 cm-1 of original infrared spectra based on the location and number of sub-peaks determined by the second derivative spectra. The curve fitting results showed that with the increase of germination time, the relative polysaccharide and protein content showed a downward trend, while the relative content of fat first decreased and then increased. The results show that FTIR combined with curve fitting can be an effective method for seed germination study.