Study On Seed Germination Of Cerealsand Legumes And The Effect Of Salt On Seed Germination By FTIR Spectroscopy

Seed germination is a classical topic in plant science.Seed germination is the first step and important development stage of plant life cycle,which is related to the smooth reproduction,evolution and agricultural production of plant population.Therefore,it is of great significance to study seed germination and seed vigor.This dissertation uses Fourier transform infrared spectroscopy and two-dimensional correlation infrared spectroscopy,combined with curve fitting,principal component analysis,and correlation analysis to analyze different germination degrees of cereals,bean seeds,as well as soybean seeds germination under salt（Na Cl,Pb Cl₂）stress.The main works are as follows:（1）The results showed that the original infrared spectra of cereal seeds with different germination degrees were basically similar,while the original infrared spectra of soybean and red bean seeds were different.The intensity ratios of several absorption peaks of carbohydrate,protein and fat in cereal and soybean seeds changed with the increase of germination time.The results of 2D-IR showed that the number and intensity of the auto-peaks,the position and intensity of the strongest auto-peaks of cereal and legume seeds in the range of 814～1000 cm^-1and 1028～1340 cm^-1changed with the increase of germination time.These results showed that the structure or relative content of sugar,protein and fat,the main nutrients in cereal and legume seeds,had obvious changes during germination.In order to further study the mobilization of three nutrients during germination,the bands of carbohydrate(1200～950 cm^-1),protein and fat(1800～1600 cm^-1)of the seeds with different germination time were analyzed by curve fitting.The results showed that with the increase of germination time,the relative content of polysaccharide and protein of cereal seeds generally decreased,the relative content of soluble sugar increased gradually,the relative content of amino acids increased first and then decreased,and the relative content of fat decreased first and then increased.However,the contents of polysaccharide and protein decreased with the increase of germination time.The relative content of fat in soybean seeds increased first and then decreased,while the relative content of fat in red bean seeds changed in the opposite way.The results showed that the physiological and biochemical characteristics of germinating cereal and legume seeds changed significantly.The storage substances were mobilized during seed germination,and their degradation caused changes in the chemical structure and content of corresponding substances.（2）The effects of two kinds of salt stress on the germination of soybean seeds were studied.The results showed that Na Cl stress inhibited the germination of soybean seeds and the growth of soybean seedlings,while the concentration of Pb Cl₂below 200 mg/L had little effect on the germination of soybean seeds,but had obvious effect on the growth of soybean seedlings.The infrared spectra of germinated soybean seeds under different concentrations of Na Cl solution and Pb Cl₂solution were basically similar,but the absorption peak intensity ratios of polysaccharide,protein and lipid changed with the increase of solution concentration.2D-IR spectra showed that the number and intensity of auto-peaks,the position and intensity of the strongest auto-peaks were different in the range of 825～1250 cm^-1and 1350～1750cm^-1under different concentrations of two salt solutions.Principal component analysis（PCA）was used to analyze the spectra of samples in the range of 1800～950 cm^-1.The results showed that there were significant differences between the experimental group and the control group.The functional groups of the substances corresponding to the peaks at 1051 cm^-1and 1745 cm^-1were the highly correlated variables of the differences among groups under Na Cl stress,while the peaks of the highly correlated variables among groups under Pb Cl₂stress were near 1747 cm^-1.The changes of sugar,protein and fat in soybean seeds under stress were further studied by curve fitting.The curve fitting results showed that with the increase of Na Cl concentration,the relative content of carbohydrate and protein increased first and then decreased,and the relative content of fat decreased gradually.With the increase of Pb Cl₂concentration,the degradation of starch,protein and fat was inhibited,the relative content of protein and fat increased first and then decreased,and the sugar did not show regular changes.The results of correlation analysis were consistent with those of principal component analysis.The accumulation and metabolism of sugar,protein and fat in soybean seeds were seriously affected by salt stress.The works of the dissertation shows that Fourier transform infrared spectroscopy is an effective method to study the effects of salt stress on seed germination and the mobilization of storage materials during seed germination.