病斑、病斑附近烟叶和正常烟叶的FTIR研究

用傅里叶变换红外光谱法研究了赤星病、角斑病和气候型斑点病3组病斑、病斑附近烟叶和正常烟叶,发现3组烟叶样品红外光谱的吸光度比A1631/A1025呈现相同的变化趋势,有正常烟叶病斑附近烟叶病斑的规律。对3组烟叶样品整个光谱区的原始光谱和二阶导数光谱进行距离分析,结果显示,病斑附近烟叶与正常烟叶的Pearson相关系数大于病斑与正常烟叶的Pearson相关系数,即与病斑相比,病斑附近烟叶与正常烟叶具有更紧密的关系。吸光度比A1631/A1025和Pearson相关系数的这种变化趋势表明病斑附近烟叶的化学成分在逐渐改变,即病斑附近烟叶处于正常和病变的过渡状态。研究结果表明,傅里叶变换红外光谱有望成为诊断烟草潜育期病害的方法。

FTIR study on the leaf spots, near-spot and normal tobacco leaves

Fourier transform infrared spectroscopy (FTIR) was used to study three group tobacco leaves of brown spot, angular spot and weather speck, with each group being composed of three samples, namely, leaf spots, near-spot and normal tobacco leaves. The results indicate that the absorption ratio A1631/A1025 of the three group tobacco leaves showed the same change tendency, with the normal tobacco leaves < the near-spot leaves < the leaf spots. For a more objective and comprehensive analysis, the original and second-derivative spectra were selected for distance analysis in the whole region. The results show that the Pearson correlation coefficient of the near-spot leaves and normal leaves is greater than the corresponding coefficient of leaf spots and normal leaves, which suggest that the near-spot leaves and normal leaves have a closer relationship compared with the leaf spots and normal leaves. The ratios of the A1631/A1025 and Pearson correlation coefficients show that the chemical composition of the near-spot leaves changed gradually, that is, the near-spot leaves were in a transient state between normal and disease leaves. In conclusion, FTIR spectroscopy is a promising technique for diagnosing tobacco disease in the incubation period.