Chin J Plan Ecolo ›› 2008, Vol. 32 ›› Issue (3): 664-672.DOI: 10.3773/j.issn.1005-264x.2008.03.016
• Research Articles •
JU Chang-Hua; TIAN Yong-Chao; ZHU Yan; YAO Xia; CAO Wei-Xing*
Aims Crop canopy reflectance, especially derivative spectrum, is a promising prospect for nondestructive rapid estimation of crop photosynthetic organ area and evaluation of crop growth status and yields. The purpose of our experiment was to investigate the quantitative relationships between derivative spectral parameters and photosynthetic organ area. Methods We used field experiments to study leaf area index (LAI), pod area index (PAI) and canopy hyperspectra reflectance of rapeseed (Brassica napus) under different nitrogen levels and in different cultivars and determined quantitative relationships between derivative spectral parameters and photosynthetic organ area. Important findings The correlation coefficient between photosynthetic organ area and derivative spectra was higher than that of canopy spectral reflectance of single band, with the best correlation at 750 nm (r=0.9). The correlation sequence of “three-edge parameters" to photosynthetic organ area was red edge＞yellow edge＞blue edge, area parameters＞amplitude parameters＞position parameters. Phenomenon of “two peak" at red edge of rape canopy spectra weakened the sensitivity of red edge position (REP) to changes of biophysical parameters, but REP extracted from linear extrapolation method (REP(le) ) strengthened it. Red edge area (SDr) and difference of SDr and blue edge area (SDb) (DSDr,b) from “three-edge parameters" and their derived parameters had the best correlation with LAI and PAI, and they were suitable for the different cultivars used in this study. Therefore, derivative spectral parameters, i.e., first derivative spectrum at 750 nm, SDr and DSDr,b could be used to effectively monitor area of photosynthetic organs in rapeseed.
JU Chang-Hua, TIAN Yong-Chao, ZHU Yan, YAO Xia, CAO Wei-Xing. RELATIONSHIP BETWEEN DERIVATIVE SPECTRA AND PHOTOSYNTHETIC ORGAN AREA IN RAPESEED (BRASSICA NAPUS)[J]. Chin J Plan Ecolo, 2008, 32(3): 664-672.
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