FTIR Spectroscopy Study Of Millet Seed Vigor

Millet has the characteristics of short growth period,strong adaptability,drought resistance,barren resistance,high water use efficiency and easy storage.It has become an important strategic reserve crop in China.At the same time,its rich nutritional value and utilization value as chemical raw materials and by-products have attracted extensive attention inrecent years.Different varieties and growing environment in different producing areas can cause the difference of millet quality,so the identification of different varieties and producing areas of millet has important reference significance for consumers.Seed vigor is an important index affecting millet production and millet quality,among which seed aging and soil salinization affect seed germination and reduce stress resistance,which can have a serious impact on yield.Therefore,it is of great significance to study seed vigor in agricultural production.In this dissertation,Fourier transform infrared spectroscopy（FTIR）and two-dimensional correlation infrared spectroscopy（2D-IR）were used to study on seed vigor of millet by combining curve fitting and principal component analysis（PCA）,in order to develop an efficient and rapid spectral method to identify millet from different varieties and origins and millet seeds with different vigor;millet seeds with different aging time and priming treatments were studied on aged millet seeds under salt stress,aiming to explore the germination characteristics and physiological characteristics of artificial aging and priming treatments with different initiators（Ascorbic acid As A,hydrogen peroxide H₂O₂）on aged millet seeds.The purpose is to provide reference for the application of millet seed safe storage and efficient artificial seedling.The main work is as follows:1.The spectral results show that the absorption peaks of FTIR spectra of millet from different producing areas are mainly composed of protein,starch and polysaccharide and lipids,and the spectrum is basically similar.In the range of1200～860 cm^-1and 1700～1180 cm^-1in 2D-IR spectra,there are obvious differences in the position,number and intensity of auto peaks and cross peaks;the spectrum in the range of 1700～1600 cm^-1（amide I region of protein）is selected for curve fitting,and the changes of the sub-peak area ratio and the protein secondary structure components can distinguish three different varieties of millet.PCA analysis can cluster millet from 9 different producing areas independently,which is mainly based on the spectral differences of fat,protein and carbohydrates.2.The vigor of millet seeds treated with different aging time was studied.The results showed that the vigor index of seeds showed a trend of first increase and then decreased during the aging process,and there was a certain difference in the anti aging ability of millet varieties.The ability of Ji Gu 1165 was better than that of Ji Gu25 seed.The infrared spectral results showed that the differences of germination seeds treated with different aging time were mainly related to the mobilization of carbohydrate,proteins and lipids.By calculating the spectral absorption peak intensity ratio,it was found that the relative contents of protein,starch and fat changed with the increase of aging time.Combined with curve fitting analysis and calculation of the corresponding characteristic peak area percentage,it can be seen that the relative content of polysaccharide generally shows an increasing trend with the extension of aging time.PCA could effectively identify millet seeds with different aging time.The loading diagram showed that the differences of fat,protein and carbohydrate contents were the main factor for principal component discrimination,in which carbohydrate played a leading role,which was consistent with the effect of artificial aging treatment on vitality index.3.Salt stress and seed aging seriously affect the germination,growth and development of millet.Therefore,the effects of seed soaking with A_SA and H₂O₂on the vitality of aged millet seeds under Na Cl stress were studied.The results showed that Na Cl stress showed that low concentration promoting and high inhibiting on seed vigor,and had little inhibitory effect on Millet seed Ji Gu 1165.The vigor of aged millet seeds of the two varieties increased first and then decreased with the increase of A_SA and H₂O₂concentration.The optimum concentrations of A_SA to improve the vigor of aged millet seeds of Ji Gu 25 and Ji Gu 1165 under Na Cl stress were 0.5mmol/L and 1.0 mmol/L,respectively;the optimum concentration of H₂O₂to improve the vigor of aged millet seeds of the two varieties under Na Cl stress is 50mmol/L,and both of the two initiators had a more significant improvement effect on the vigor of Ji Gu 1165 seeds.In order to further understand the mobilization of nutrients,curve fitting analysis was carried out on the infrared spectra in the ranges of polysaccharide,protein amide I and fat,and the corresponding sub-peak area percentage was calculated.The results showed that with the increase of the priming concentration,the relative contents of soluble carbohydrate in the aged seeds of the two cultivars showed a trend of first increase and then decrease during the germination process;the relative contents of protein and fat in the aged seeds of Ji Gu 25 increased with the germination process.The increase of trigger concentration first decreased and then increased.The relative content of protein first decreased and then increased,and the relative content of fat increased first and then decreased with the increase of trigger concentration in the aging seeds of Ji Gu 1165 during germination.The results of PCA showed that As A priming treatment may have a great effect on the carbohydrates in the germination of two kinds of aging seeds.PCA results showed that different initiation treatments of A_SA may have a great impact on the carbohydrates in the germination process of the two aged seeds.H₂O₂can more effectively trigger the germination of aging Ji Gu1165 seeds under Na Cl stress,and has a significant impact on its carbohydrate,protein and fat.This can be used as a classification basis to identify the germinated seeds treated with different concentrations of initiators.In conclusion,the response process of different crop seeds to priming is different.The germination effect of Ji Gu1165 aging millet seeds under Na Cl stress induced by soaking seeds with 50 mmol/L H₂O₂is the best and the vigor is the highest.The work of the dissertation shows that FTIR spectroscopy can be used to identify varieties and producing areas of millet,and it is expected to be a fast and effective method to distinguish seed vigor.