Research Of Selenium Content In Buckwheat Grains Based On Hyperspectral Analysis

China is one of the main buckwheat production countries.Selenium-rich buckwheat has important nutritional value and it is the ideal nutritious food in the future life of human.It has productive and practical significance to realize the rapid and non-destructive estimation of selenium content in buckwheat kernel.Hence,"Hongshan buckwheat" was as the experimental material in this study and sodium selenite(Na2SeO3)and selenium-enriched fertilizers were sprayed only once on the blade surface of "Hongshan buckwheat" at the full flower period.In addition,the canopy spectra,grain selenium content and main agronomic parameters of leaf area index(LAI),SPAD and aboveground biomass were measured at the different stages of "Hongshan buckwheat" after the foliar fertilization.Moreover,the relationship between grain selenium content with main agronomic parameters(LAI,SPAD and aboveground biomass)and the constructed vegetation indexes were analyzed.According to the research idea of "vegetation indexes-main agronomic parameters-grain selenium content",the monitoring models of buckwheat grain selenium content based on the spectral vegetation indexes were established,and the results showed that:1.The canopy spectral reflectance existed certain differences in different growing periods.In the full wavebands region,the spectral reflectance decreased with the advancement of the growth period,and the reflectance changed obviously in the near-infrared region.The waveband position of 680 nm represented an absorption valley.Moreover,the spectral reflectance characteristics had no obvious peak and valley at the maturation stage of "Hongshan buckwheat",which showed no spectral characteristics of typical green vegetation.Under different selenium level,the canopy reflectance in the whole growth period of buckwheat showed no obvious change in the visible region,however appeared some differences in the near-infrared region.The selenium level of Sel,Se2 and Se3 had the high reflectance value and Se4 emerged the lowest reflectance value.In addition,The reflectance value of F1,F2 and F3 appeared that:F1>F2>F3.2.With the increase of selenium concentration,The value of LAI,SPAD and the aboveground biomass showed the variation trend of increasing at first and then decreasing.Under the same selenium level,the LAI,SPAD and aboveground biomass also represented the same change trend.3.The important wavebands of different growth indexes were elected by using the successive projections algorithm(SPA)method,and the important wavebands of LAI,SPAD and the aboveground biomass located at the positions of 581,696 and 1393 nm;585,697 and 1393 nm,and 401,703 and 1146 nm,respectively.4.The correlation between different vegetation indexes with main agronomic parameters of buckwheat and the correlation between the grain selenium content of buckwheat with the corresponding agronomic parameters were analyzed.In addition,the monitoring model of grain selenium content was constructed based on the vegetation index of SPAD,and the model expressed that:Y=0.0289(46.383e-0.632N)2-2.0993(46.383e-0.632N)+38.51.The model accuracy was 0.757,which indicated that the grain selenium content of buckwheat could be accurately monitored by using the hyperspectraltechnology.