[Measurement of Nitrogen Content in Lettuce Canopy Using Spectroscopy Combined with BiPLS-GA-SPA and ELM].

Nitrogen fertilizer is necessary to improve yield and quality of lettuce. Spectroscopy is one of the most effective techniques used to detect crop nitrogen content. In this study, canopy reflectance spectra were acquired under five levels of nitrogen, and then were Savitzky-Golay smoothed, the first-order derivative spectra were calculated from the smoothed spectra to eliminate noise effects.

Detection of meat-borne trimethylamine based on nanoporous colorimetric sensor arrays.

Trimethylamine (TMA) is a key measurement indicator for meat spoilage. In order to develop simple, cheap, and sensitive sensors for TMA detection, a nanoporous colorimetric sensor array (NCSA) was developed. A sol-gel method has been used to obtain TiO2 nanoporous film as substrate material to improve the sensitivity and stability of the CSA.

[Study on the polarized reflectance-hyperspectral information fusion technology of tomato leaves nutrient diagnoses].

With 25%, 50%, 75%, 100% and 150%, five levels of, nitrogen (N), phosphorus (P) and potassium (K) nutrition stress samples cultivated in Venlo type greenhouse soilless cultivation mode as the research object, polarized reflectance spectra and hyperspectral images of different nutrient deficiency greenhouse tomato leaves were acquired by using polarized reflectance spectroscopy system developed by our own research group and hyperspectral imaging system respectively. The relationship between a certain number of changes in the bump and texture of non-smooth surface of the nutrient stress leaf and the level of polarization reflected radiation was clarified by scanning electron microscopy (SEM). On the one hand, the polarization spectrum was converted into the degree of polarization through Stokes equation, and the four polarization characteristics between the polarization spectroscopy and reference measurement values of N, P and K respectively were extracted.

[Study on the polarized reflectance characteristics of single greenhouse tomato nutrient deficiency leaves].

In order to improve accuracy of quantitative analysis model for the greenhouse tomato nitrogen, phosphorus and potassium nutrient stress, and explore the advantages of polarization non-destructive detection in single-leaf plants scale, polarized reflectance characteristics of greenhouse nutrient deficiency tomato leaves in different growing seasons and different deficiency extents were both examined via means of polarized reflectance spectroscopy system, which was self-developed by the research group. The main factors with effects on the polarized reflectance characteristics of tomato leaves were discussed, such as incident zenith angle, azimuth angle, detection zenith angle, light source polarizer degree, and detector polarizer degree. Experiments were carried out to verify the optimum level of above five parameters by means of range analysis of orthogonal experiments, through that way we can know the best angle combination of five parameters.

[Identification of lettuce leaf nitrogen level based on adaboost and hyperspectrum].

In order to facilitate lettuce fertilization in an economically rational way, an intelligent method to identify lettuce leaf nitrogen levels was studied. Lettuce samples of different nitrogen levels were cultivated in greenhouse with soilless cultivation method. In a particular growth period, the lettuce samples in various nitrogen levels were collected, then the FieldSpech3 spectrometer was used to acquire the hyperspectral data of the cultivated lettuce leaves.

[Rapid diagnostics of early phosphorus deficiency in mini-cucumber plants under protected cultivation by near infrared spectroscopy].

The morphological symptom of phosphorus deficiency at early stage is similar to the appearance of leaf aging process in preliminary phase, so that visual diagnostics of phosphorus deficiency in mini-cucumber plants at early stage is practically impossible. Near infrared reflectance spectra contain information about differences in compositions of leaf tissues between phosphorus-deficient plants and healthy plants. In the present paper, near infrared reflectance spectroscopy was used to provide diagnostic information on phosphorus deficiency of mini-cucumber plants grown under non-soil conditions.

[Research on distinguishing weed from crop using spectrum analysis technology].

Automatic detection of weeds is necessary for site--specific application of herbicides or precise physical weed control. Leaf reflectance is mainly determined by photosynthetic pigments, leaf structural properties and water content, so spectral reflectance characteristics can be used for weed discrimination. The spectral reflectance of cotton, rice and weeds was determined in the range from 350 to 2 500 nm using the Analytical Spectral Device Full Range FieldSpec Pro (ASD) in laboratory.

[Determination of total nitrogen content in fresh tea leaf using visible-near infrared spectroscopy].

To monitor tea tree growth and nitrogen nutrition in tea leaves, visible-near infrared spectroscopy was used to determine total nitrogen content. One hundred eleven fresh tea leaves of different nitrogen levels were sampled according to different tea type, plant age, leaf age, leaf position and soil nutrients, which covered a wide range of nitrogen content. Visible-near infrared reflectance spectra were scanned under the sunlight with a portable spectroradiometer (ASD FieldSpec 3) in field.