Abstract
From 2006 to 2007, two experiments were carried out to find out the spring wheat canopy and leaf spectral characters and the growth status non-destructively monitoring. The results are following: Firstly, that the spectral differences are clear for the canopy and leaves of spr-wheat under different density levels, and the canopy spectral reflectance are gradually getting smaller in the visible region and bigger in the near infrared region along with density level increasing at jointing, booting, heading and filling stage. The difference of the spectral reflectance of the leaf from the top on the main stem is little in the visible region and great in the near infrared region at nutrition grown stage; Secondly, In the different growth stage, the hyperspectral reflectance of the canopy level and the leaf level are different, and that of the canopy is highest at jointing stage and lowest at ripening stage in the visible region and in the shortwave and the spectral variation trend is similar, meanwhile, that is highest at flowering~filling stage in the near infrared region. The green peak disappeared at ripening stage. On the contrary, the leaf hyperspectral reflectance is highest at jointing stage than other stage in the near infrared region, and the reflectance in green region is falling at ripening stage. Thirdly, Correlation between spr-wheat variable and canopy and leaf reflectance were analyzed, The results revealed that wheat variables showed positive correlation with reflectance at near-infrared bands and negative at visible wavelength range. Five variables: The leaf area indices (LAI), the above ground fresh biomass (FW), above ground dry biomass (DW), plant height (PH) and chlorophyll showed very similar patterns potentially due to high correlation among three spr-wheat variables. The high correlation coefficient between reflectance at waveband 760-1100 nm (near-infrared) and 670-690 nm (red) with spr-wheat species variables indicated that reflectance at these wavebands might be important for monitoring spr-wheat growth status .Additionally, LAI,AFB, ADB, PH and chlorophyll are significantly correlative to the spectral indices: normalized difference vegetation index (NDVI), enhanced vegetation index (EVI ), soil adjusted vegetation index (SAVI), ratio vegetation index (RVI) ,difference vegetation index (DVI) and perpendicular vegetation index (PVI). and the relationship of PVI with plant height and above FW is the best (R=0.653,P<0.01;r=0.748,P<0.01), and the LAI have the best relationship with DVI (r=0.694,P<0.01) and the relativity are the relationship between the lambda red and the chlorophyll is the best (r=957,P<0.01), the slope of red edge (D lambda red ) and plant height (PH) are good correlation. This indicated that some right spectral variables would be used to estimate the LAI, AFB, ADB the PH and chlorophyll for spr-wheat.
Published Version
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