Effects Of Low Temperature And Saline-alkila Stress On Seed Germination Of Grain Seeds Guided By FTIR Spectroscopy

Seed germination is the beginning of plant life process,seed germination directly affects the final crop yield.Seed germination is often affected by low temperature and soil salinization,which seriously threatens the safety of food production.In this thesis,the effects of low temperature on the germination of grain seeds（quinoa,highland barley,rice and wheat）and the effects of low temperature combined with salt stress on the germination of highland barley seeds were investigated by FTIR combined with curvile-fitting.The works are as follows:1.The results showed that the germination potential,germination rate and germination index of the four grain seeds decreased with the decrease of temperature,and the germination rate and germination index of highland barley seeds were still higher at 4℃.Low temperature stress inhibited the germination of four kinds of grain seeds,and the highland barley seeds were more resistant to low temperature.Under low temperature and saline-alkali stress,the germination potential,germination rate and germination index of highland barley seeds decreased with the increase of saline-alkali concentration,but the decline was more obvious under Na₂CO₃stress.2.The results of IR showed that the original infrared spectra of grain seeds under low temperature and saline-alkali stress were similar,mainly composed of characteristic absorption peaks of polysaccharide,fat and protein.Under low temperature and saline-alkali stress,the positions of absorption peaks in the second derivative infrared spectra（SD-IR）of grain seeds were similar in the range of1800～800 cm^-1,but the intensity of several absorption peaks changed with the change of temperature and saline-alkali concentration.In the range of 850～1350 and1350～1800 cm^-1,there were differences in the number,position,intensity,position of the strongest auto-peak and the substrong auto-peak,number and position of the weak auto-peak of the four kinds of grain seeds under low temperature stress.The results indicated that the contents or structure of stored fat,protein and carbohydrate in grain seeds germinated had been changed under low temperature and saline-alkali stress.3.With the decrease of temperature,the curve fitting analysis for polysaccharide(1200～950 cm^-1)and amideⅠbelt(1700～1600 cm^-1)showed that the polysaccharide content of highland barley and wheat seeds increased firstly and then decreased.The polysaccharide of quinoa seeds increased.The polysaccharide content of rice seeds showed a decreasing trend.The protein content of quinoa seed decreased gradually.The protein content of highland barley seeds increased firstly and then decreased.The protein content of rice seed increased gradually.The protein content of wheat seeds decreased firstly and then increased.In addition,the secondary structure of proteins in seeds of the four grains was changed.The results showed that under low temperature stress,polysaccharide content,protein structure and content in seeds of four kinds of grain seeds changed.At low temperature of 15℃,with the increase of Na Cl concentration,the polysaccharide content in highland barley seeds increased firstly and then decreased,while the protein content increased.At low temperature of4℃,with the increase of Na Cl concentration,the contents of polysaccharide and protein in highland barley seeds showed a decreasing trend.At low temperature of15℃,with the increase of Na₂CO₃concentration,the polysaccharide content in highland barley seeds decreased firstly and then increased,while the protein content decreased gradually.At low temperature of 4℃,with the increase of Na₂CO₃concentration,the polysaccharide content in highland barley seeds gradually decreased,and the protein content gradually increased.In addition,the secondary structure of protein in highland barley seeds was changed.The results showed that polysaccharide content,secondary structure and content of protein in highland barley seeds changed under low temperature and saline-alkali stress.The results showed that Fourier transform infrared spectroscopy combined with curve fitting analysis was an effective method to study the effects of low temperature and saline-alkali stress on seed germination.