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氮肥等級與刈割頻度度對Tifway 419百慕達草反射光譜之影響

Nitrogen Rate and Mowing Frequency Effects on Spectral Reflectance of Bermudagrass "Tifway 419" (Cynodon transvaalensis x C. dactylon)

Abstracts


The objectives of this study were conducted to examine the contents of pigments in the leaves and vegetation reflectance spectrum of bermudagrass ”Tifway 419” (Cynodon transvaalensis x C. dactylon) with different nitrogen application rates and mowing frequencies. The contents of chlorophyll (Chl), its biosynthetic and degradative intermediates (total porphyrin; chlorophyllide, Chlide; pheophytin, Phe; phytylated and dephytylated pigments), and carotenoids in the leaves of bermudagrass Tifway 419 elevated with increasing nitrogen rates. The mole percents of three porphyrins (protoporphyrin, PPIX; magnesium protoporphyrin IX, MGPP; protochlorophyllide, Pchlide) were not influenced by nitrogen application rate significantly. The canopy reflectance spectra of bermudagrass Tifway 419 were measured. The reflectance in the range of 400 to 700 nm was very low, while near-infrared (NIR) band above 750 nm was very high. The reflectance in the near-infrared wavebands was increased with increasing nitrogen application rate, but the reflectance in the visible region was decreased as nitrogen application rate increased. Spectral indices NDVI680, NDVI705, and NDVIbroad calculated using broad-band reflectance were correlated well with the contents of Chl a, Chl b, and Car (R^2 about 0.7, p<0.01). The chlorophyll-related compounds containing phytol chain greatly contributed to changes in NDVI than those compounds without phytol chain, except for Chl b. The LP Car also played a more important role in NDVI change than the MP Car. Results suggest that NDVI calculated from vegetation reflectance spectra was more affected by the chlorophyll- and carotenoid-related compounds located onto the thylakoid membranes than those located in the stroma of chloroplast.

Parallel abstracts


The objectives of this study were conducted to examine the contents of pigments in the leaves and vegetation reflectance spectrum of bermudagrass ”Tifway 419” (Cynodon transvaalensis x C. dactylon) with different nitrogen application rates and mowing frequencies. The contents of chlorophyll (Chl), its biosynthetic and degradative intermediates (total porphyrin; chlorophyllide, Chlide; pheophytin, Phe; phytylated and dephytylated pigments), and carotenoids in the leaves of bermudagrass Tifway 419 elevated with increasing nitrogen rates. The mole percents of three porphyrins (protoporphyrin, PPIX; magnesium protoporphyrin IX, MGPP; protochlorophyllide, Pchlide) were not influenced by nitrogen application rate significantly. The canopy reflectance spectra of bermudagrass Tifway 419 were measured. The reflectance in the range of 400 to 700 nm was very low, while near-infrared (NIR) band above 750 nm was very high. The reflectance in the near-infrared wavebands was increased with increasing nitrogen application rate, but the reflectance in the visible region was decreased as nitrogen application rate increased. Spectral indices NDVI680, NDVI705, and NDVIbroad calculated using broad-band reflectance were correlated well with the contents of Chl a, Chl b, and Car (R^2 about 0.7, p<0.01). The chlorophyll-related compounds containing phytol chain greatly contributed to changes in NDVI than those compounds without phytol chain, except for Chl b. The LP Car also played a more important role in NDVI change than the MP Car. Results suggest that NDVI calculated from vegetation reflectance spectra was more affected by the chlorophyll- and carotenoid-related compounds located onto the thylakoid membranes than those located in the stroma of chloroplast.

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