Using field spectroscopy for detecting chlorophyll content on Valencia orange in the arid region

Abstract

Filed spectroscopy is a modern tool for studying crop characteristics. The main objective of the current study is to use field spectroradiometer ASD-4 to generate remotely sensed empirical chlorophyll content models to estimate Chl. (a,b and total chlorophyll) on Valencia orange under arid region and determine which spectral band on the spectrum recognize to chlorophyll content . The main input parameters of these models are spectral data either in the form of spectral reflectance data released from Field spectroradiometer ASD-4 in the form of spectral vegetation indices. The spectral bands ranged from 350 nm to 2500 nm to select the best band to recognize chlorophyll content. The four vegetation indices that are forms of ratios between red and near-infrared bands are (Chlorophyll Index Red Edge 710, Simple Ratio 695/760, Red-Edge Position Linear Interpolation and Normalized Difference NIR/Red). This aim was achieved by select field in wadi elmolak, Ismaeilia rejoin, Egypt, 42 samples were collected and produce Partial least Square model (PLS) between laboratory (Chl. a,b and carotein) contents and field spectroradiometer as well as PLS between field measurements of chl. using (CM-1000) and laboratory measurements in the study area. Many statistical procedures, including a principal component analysis (PCA), multiple linear regression model (MLR), PLS were used. Correlation co-efficient between actual and predicted between physiochemical chlorophyll a,b and total properties (Chlorophyll Index Red Edge 710, Simple Ratio 695/760, Red-Edge Position Linear Interpolation and Normalized Difference NIR/Red), CM-1000 and spectroscopy data of coefficient of determination (R2) were R2 = 0.912,0.727, 0.864 and 0.918 and 0.817 respectively. On thr other hand the selection band to determine the best wavelength to determine chlorophyll content was W- 504 with high accuracy R2 0.734. It is complemented that the VIS-NIR-SWIR spectroscopy study can be effectively tool for studied chlorophyll properties. Also, PLS is a good tool for detecting the relationships between spectral properties and Lab. Measurements