Monitoring Growth Status of Spring Wheat in Rainfed Agriculture Area in Loess Plateau with Hyperspectral Reflectance Data at Canopy and Leaf Level

摘要

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 sprleaf reflectance were analyzed, The results revealed that wheat variables showed positive correlation with reflectance at near-infrared bands and negative at visible wavelength range.