| Rice is one of main grain crops of our country with a long history. Rice in cold region is grows in northeast China, and generally belongs to single-crop late-maturing rice variety. Rice blast is one of the most important diseases for rice which occurs every year. It cuts the production by10～20%in epidemic year and even40%～50%in serious cases. In recent years, to improve the quality of the rice, high quality varieties are grown in large quantities. It causes singleness of the variety and increases the amount of the application of nitrogen fertilizer for which the impact of rice blast is gradually serious year after year. Although the planting area of Heilongjiang Reclamation Area is relatively small, it has become the important commodity grain base of our country because of its small population, great potential, high quality of rice, and high commodity rate. The area suffered pests and disease is very large every year in reclamation area, and it causes great damage to our country and peasants. To steady rice yield in the northeast of China and construct the base of green organic rice, it needs to rely on scientific and technological progress to solve the bottleneck on the development of rice. Rice blast as the main disease which influences stable and high yield, its internal pathogenesis and the pathogenesis of destroying the rice structure are the main research directions for many research workers. Based on the research results of Raman spectra and near infrared spectroscopy at home and abroad, this paper deeply and detailedly studies for rice. It extracts the related physiological information by combining technology of Raman spectra and the information of rice plant disease, and implements the omnidirectional detection and diagnosis of blast of rice in cold region using used the of chemical and biomolecular approach. The contents and achievements of this study are presented as follows:1. The detection data of blast of rice in cold region have been analyzed by near infrared spectroscopy technique. This study uses WQF-600N Fourier transform near-infrared spectrometer to collect near infrared spectroscopy of different parts such as stems, leaves, and grains of both healthy plants and infectious ones. The spectra are analyzed. To healthy plant, the results show that the spectral transmittance of stem has a high coherence with that of grain, and the spectral transmittances of leave and grain are higher than that of stem, but their difference is small. To infectious plants, the spectra of three kinds of plants of different infectious degrees which can be distinguished by naked eyes are collected. The results show that the spectral transmittance of stem of the most severely infectious plants is the highest, and it becomes lower as the infectious degree decreases. The analysis of single near infrared spectra line shows that, as the wave number decreases, the difference of the transmittance strength becomes smaller, and the difference is big when the wave number is large. Besides spectra comparison between stems, leaves and grains, the spectra of infectious grains of five infectious degrees are also analyzed. The grains selected by measuring the plumpness are divided to five infectious degrees, of which near infrared spectroscopy is analyzed and researched in a graded quantitative way. During the research, it is found that the variation of spectra is not perfectly according with that of practical infectious degree. We accurately analyze the internal problem of Fourier transform near-infrared spectrometer, the problems caused by fast Fourier transform, the apodizing peak distortion of data, and the error of near infrared spectroscopy. Those analysises provide a convincing theoretical foundation for more accurately analysis of spectra.2. The chemical bond of infectious rice in cold region has been analyzed by Raman spectra method. The characteristic frequency laws of some kinds of vibrations are proposed, such as stretching vibration, rocking vibration and asymmetrical stretching vibration of saturated group (like CH3and CH2of saturated hydrocarbon, sulfhydryl and double sulfur bands), unsaturated group (like carbon-carbon double bond, carbon-carbon triple bond, carbon-hydrogen double bond, carbon-hydrogen triple bond, double bond of carbon to oxygen and aromatic ring), and special group (like C=O=C、C—O—C、N=C—N). On that basis, the characteristic frequencies of group of both healthy rice and infectious one plant in Raman spectra are identified under different exposure times (from1-6seconds) and different light sources including high, moderate and low intensity respectively. To the stretching vibration of C=C double bond which has the strongest Raman intensity, its characteristic frequencies are identified to be1522cm-1and1516cm-1. The characteristic frequency of C—C single bond is identified to be1160cm-1. The characteristic frequencies of rocking vibration out of plane of carbon-hydrogen bond and methyl are also analyzed, and its result is summarized in chart form. On that basis, the characteristic peaks of the whole Raman lines ranging from600cm-1to2900cm-1are identified and analyzed. We also make association analysis to internal structure of rice leaves and some characters such as secondary carbon, tertiary carbons, fourth carbon, and line broadening. To both healthy leaves and infectious ones of rice in cold region, the analyzed results of most of the key chemical bonds are got in Raman spectrum approach.3. The Raman characteristic frequency offset of chemical bond influenced by rice blast is researched. To plants in different infectious degrees, we statistically analyze some functional groups such as the spectral peak of C—N stretching vibration and the spectral peak of characteristic frequency of carbon-carbon double bond vibration. Due to the limited ability to differentiate of human eyes, data are analyzed the under conditions of having distinguished the healthy leaves and infectious ones. It can be seen that the infectious grades of blast can be classified according to the frequency offset at all. It is also obtained by analyzed that, for the error of human eyes to judge whether the rice is infectious blast, some frequency distribution of the health leaves judged by human eyes is overlapping with that of infectious ones in the view of statistical frequency distribution. On the basis of statistical frequency distribution, some typical offset spectral peaks are analyzed. It can be seen that, although the offset directions are different for different Raman spectral peaks, the relationship between spectral peak offsets still can be found according to different infectious degrees. The characteristic frequency peak of828cm-1is most typical in this part. At the same time, the relationship between variation of spectral peak and the infectious degrees of blast can be built. All of those provide a analysis method to diagnose blast.4. The secondary structures of protein and genetic material in rice plant are estimated and analyzed quantitatively. It analyzes the different chemical structures of blast fungi, rice cells, and some macromolecular substances such as chitin, cellulose and cysteine. On that basis, it quantitatively estimates and analyzes the secondary structures of the genetic material and the protein which compose rice cells. Firstly, it analyzes some information in protein such as a-helical, β-pleated sheet, p-turn and random coil, and conformation groups which contain carboxyl (), sulfhydryl (—SH), S—S bond and C—S bond. Besides, to the structure of amide, the conformation sensitive spectral lines of six peaks, and the quantitative relationship of buried proportion and emerged proportion of tyrosine residue are analyzed. It analyzes the corresponding relationships between the spectral peaks and conformations of gauche-gauche-gauche conformation, gauche-gauche-trans configuration, and trans-gauche-trans conformations of S-S bond in phenylalanine. Secondly, it analyzes the corresponding conformation of DNA, RNA and four kinds of deoxynucleotides in genetic material. The spectral lines of phosphate backbone group in RNA and DNA, and of phosphate ions and phosphodiester are also analyzed. Finally, ribose as the auxiliary material of genetic material is identified and conformationally analyzed correspondingly. Although the structure of protein can not be represented in three-dimension finally, it gives the comprehensive analysis and explanation in secondary structure layer. Those achievements can provide theoretical and practical guide to the spectra technology diagnosing blast of rice in cold region.5. The mechanism and the method of early diagnosing blast for rice in cold region are researched. By the method of using the scattering cross section of Raman spectra, it analyzes the scattering cross section’s variation of spectral lines of characteristic functional groups’and the sensitive spectrum of rice blast with the infectious degrees, and proposes the method of diagnosing rice blast according to scattering cross section. By autocorrelation analysis to Raman spectra, it can be obtained that there is no obvious corresponding relationship between the infectious degrees and the correlation coefficient of spectral data. The sensitivity of diagnosing blast is improved by employing the relative Raman spectral strength which is sensitive to rich blast. On that basis, the method of early diagnosing blast for rice in cold region is proposed.The research results show that, the method of using relative Raman spectral strength which is sensitive to rich blast, and the detection method of using near infrared spectroscopy provide theoretical basis and detection method to early diagnosing blast for rice in cold region, and powerful guarantees for preventing disease to rice. |
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