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Plant canopy pigment concentration is a critical variable for agricultural remote sensing due to its close relationship to leaf nitrogen content. The aims of this study were to: (1) compare the prediction performances on chlorophyll, chlorophyll-a and b, and carotenoid concentration in jujube leaf at canopy scale between partial least squares regression (PLSR) and support vector machine (SVM), (2) develop quantitative models to estimate pigment concentration in jujube canopy using hyperspectral data and provide theoretical and technical support for rapidly, non-destructive, less expensive and eco-friendly measuring the concentration. Results from correlation analysis showed that jujube canopy pigment concentration correlated strongly with hyperspectral data. What’s more, the hyperspectral data was better correlated by chlorophyll and chlorophyll-a than chlorophyll-b and carotenoid. Results of independent samples tested in predicting performance indicated that both of the PLSR and SVM models could effectively estimate pigment concentration, however, with different prediction precisions. Additionally, the precision of SVM outperformed PLSR for predicting chlorophyll and carotenoid. Whereas chlorophyll-a and chlorophyll-b were better predicted using PLSR than SVM. Compared among all the pigments’ prediction precisions with corresponding optimal inversion models showed that prediction precisions on chlorophyll, chlorophyll-a and carotenoid were superior to chlorophyll-b. The determination coefficients and residual prediction deviation from predicting chlorophyll, chlorophyll-a and carotenoid were higher than 0.8 and 2.0, respectively, while the mean relative error values were lower than 13%. And the corresponding values from predicting chlorophyll-b were 0.60%, 20.79% and 1.79% respectively.

The precipitation of floating and sinking dust on leaves of plants is called as foliar dustfall. To monitor foliar dustfall, it will provide fundamental basis for environmental assessment and agricultural disaster evaluation of dust area. Therefore, the aim of this work to (1) study the effect of foliar dustfall content (FDC) on high spectral characteristics of pear leaves, (2) analyze the relationship between reflectances and FDC, and (3) establish high spectral remote sensing quantitative inversion model of FDC. The results showed that FDC increased reflectances of visible band (400~700 nrn) with maximum band of 666 nm. Absolute and relative rates of change were -10. 50% and -62. 89%, respectively. The FDC decreased reflectances of near infrared band (701 ~ 1 050 nm) with maximum band of 758 nm. Absolute and relative rates of change were 12. 04% and 41. 75%, respectively. After dustfall was removed, reflection peak of green light and absorption valley of red and blue light became prominent, and slope of 500~750 nm wake band increased when FDC was more than 20 g . m-2. While FDC just slightly affected shape and area of reflection peak of green light when FDC was less than 20 g . m-2. FDC were positive and negative correlated with reflectances of visible band and near infrared band, respectively. Maximum correlation coefficient (0. 61) showed at 663 nm. All of 7 inversion models, the model based on the first-order differential of logarithm of the reciprocal had better stability and predictive ability. The coefficient of determination(R2), root mean square error (RMSE) and relative percent deviation (RPD) of this model were 0. 78, 3. 37 and 2. 09, respectively. The results of this study can provide a certain reference basis for hyperspectral remote sensing of FDC.

The objective of the present article is to ascertain the mechanism of hyperspectral remote sensing monitoring for soil salinization, which is of great importance for improving the accuracy of hyperspectral remote sensing monitoring. Paddy soils in Wensu, Hetian and Baicheng counties of the southern Xinjiang were selected. Hyperspectral data of soils were obtained. Soil salt content (S(t)) an electrical conductivity of 1:5 soil-to-water extracts (EC(1:5)) were determined. Relationships between S(t) and EC(1:5) were studied. Correlations between hyperspectral indices and S(t), and EC(1:5) were analyzed. The inversion accuracy of S(t) using hyperspectral technique was compared with that of EC(1:5). Results showed that: significant (p<0.01) relationships were found between S(t) and EC(1:5) for soils in Wensu and Hetian counties, and correlation coefficients were 0.86 and 0.45, respectively; there was no significant relationship between S(t) and EC(1:5) for soils in Baicheng county. Therefore, the correlations between S(t) and EC(1:5) varied with studied sites. S(t) and EC(1:5) were significantly related with spectral reflectance, first derivative reflectance and continuum-removed reflectance, respectively; but correlation coefficients between S(t) and spectral indices were higher than those between EC(1:5) and spectral indices, which was obvious in some sensitive bands for soil salinization such as 660, 35, 1229, 1414, 1721, 1738, 1772, 2309 nm, and so on. Prediction equations of St and EC(1:5) were established using multivariate linear regression, principal component regression and partial least-squares regression methods, respectively. Coefficients of determination, determination coefficients of prediction, and relative analytical errors of these equations were analyzed. Coefficients of determination and relative analytical errors of equations between S(t) and spectral indices were higher than those of equations between EC(1:5) and spectral indices. Therefore, the responses of high spectral information to St were more sensitive than those of high spectral information to EC(1:5). Accuracy of St predicted from high spectral data was higher than that of EC(1:5) estimated from high spectral data. The results of this study can provide a theoretical basis to improve hyperspectral remote sensing monitoring accuracy of soil salinization.

The influences of iron oxide on soil reflectance, soil line parameter, organic matter spectral characterization and the shape of soil reflectance spectra were studied in the present paper with thirteen samples in several soil types, which covered a range of iron oxide content obtained from various combination of original and iron-removing samples. The results highlight that (1) a decrease on 350-570 nm and an increase on 570-2 500 nm were showed in the reflectance spectra with increasing iron oxide content. However, there was no significant correlation between iron oxide and spectral reflectance quantitatively; (2) iron oxide content had a negative linear correlation with soil line slope and a positive linear correlation with intercept, both were significant, which illustrated the feasibility of iron oxide prediction using soil line parameter; (3) the spectral characteristics of soil organic matter could be covered by iron oxide on 622-851 nm; (4) iron oxide in soil had influence on the shape of reflectance spectra after continuum removal and calculating statistical F and spectral angle.

The method is based on the enhancement effect of the resonance light-scattering (RLS) of pararosaniline by DNA. In the pH rang of 0.5-1.5, the enhanced intensity of pararosaniline RLS at 355 nm is proportional to the concentration of DNA in the rang of 0.20-15 micrograms.mL-1. The detection limit is 36 ng.mL-1. This method is simple, rapid and has been applied satisfactorily to the determination of DNA in mixed samples.

A new selective and sensitive spectrofluorimetric method for the determination of Tyrosine in beer and grape wine has been developed. This method is based on the quenching of fluorescence of Tyrosine by Molybrum(VI). The exitation and emission wavelengths were found to be 278 and 305 nm, respectively. There was a linear relationship in the range of 0.01-14.4 micrograms.mL-1 for Tyrosine. This method is simple and rapid, and has been applied to the determination of Tyrosine in beer and grape wine with satisfactory results.

The method is based on the enhancement effect of the resonance light scattering (RLS) due to the long range assembly of neutral red (NR) on the molecular surface of DNA. The RLS of NR is greatly enhanced by DNA in the pH range of 5.0-7.0. The enhanced intensity of RLS at 335.0 nm is proportional to the concentration of DNA in the range 0-600 ng.mL-1. The detection limit is 12.8 ng.mL-1. This method is simple, rapid and has been applied to the determination of DNA in mixed samples with satisfactory results.

The resonance light scattering (RLS) spectra of Rosaniline with DNA have been studied. The RLS of Rosaniline is greatly enhanced by DNA in pH range of 10.5-10.8. There is a resonance light scattering peak ofat 485 nm, and the enhanced intensity of RLS at this wavelength is proportional to the concentration of DNA. The linear range of the calibration graph is 0-1.00 mg.L-1 with the correlation coefficient of 0.9980. The detection limit is 14.2 ng.mL-1. The relative standard deviation(n = 10) was within 2.1%. This method is simple, rapid and has been applied to the determination of DNA in mixed samples with satisfactory results.