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題 名 | 水稻族群植冠反射光譜之分析=Analysis of Reflectance Spectrum of Rice Canopy |
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作 者 | 楊純明; 蘇慕容; | 書刊名 | 中華農業氣象 |
卷 期 | 4:2 1997.04[民86.04] |
頁 次 | 頁87-95 |
分類號 | 434.113 |
關鍵詞 | 水稻; 植冠; 反射光譜; 反射比; 植被指數; 葉面積指數; Rice; Canopy; Relfectance spectrum; Reflectance; Vegetation index; Leaf area index; |
語 文 | 中文(Chinese) |
中文摘要 | 為瞭解田間水稻族群植冠反射光譜之特性與變化趨勢,本試驗特利用攜帶式輻射 光譜層析儀遙測 1996 年一、二期稻作全生育期植冠反射光譜,據以探討、分析各波段隨生 育進展的演變、植被指數的改變、及近紅外光反射比與葉面積指數的關係。解析反射光譜的 波長範圍介於 350 ∼ 1100 nm,包含紫外光、可見光及近紅外光等波段。 根據試驗結果, 水稻兩期作植冠反射光譜在紫外光及可見波段 (350 ∼ 700nm) 範圍內,除了生育初期及成 熟期外,其餘時期反射比值皆小於 15 %。近紅外光波段 (740 ∼ 1100 nm) 反射比值於全 生育期間維持在 30 ∼ 55 %範圍之間,而以生育初期及後期之反射比值較低。由特定紅光 (674 nm) 及近紅外光 (756nm) 波長所計算之植被指數如標準植被指數差 (NDVI)、 植被植 數比 (RVI)、土壤校正植被指數 (SAVI)、及植被指數差 (DVI) 等四項發現,植被指數隨水 稻生育之進展呈近似鐘形曲線,並可顯現出一、二期稻作間生長差異之時間落差。 以 NDVI 為例,若將生育日數經時間標準化轉換後,則兩期稻作之變化類似。水稻葉面積指數與近紅 外光 (以 756nm 為例 ) 反射比關係以 Mitscherlich function 之對數函數表示之適用性 甚佳,可利用於估算水稻全生育期葉面積指數的變化。 |
英文摘要 | The reflectance spectrum of crop canopy changes with time and space and is a function of growth status. Analysis of reflectance spectra of a crop during the growing period can help in characterizing and evaluating the spectral property and growth performance of that crop. Field experiments were carried out to remotely measure and analyze the reflectance spectra, in the range of 350 ∼ 1100 nm, of rice canopy in the first and the second growing seasons of 1996. Data indicated that, except in the early growth and grain-filling stage, reflectance within 350 to 700 nm region was lower than 15% in both crops. Reflectance of wavelengths above 740 nm was maintained in 30 ∼ 55%. By using two specific wavelengths of 674 nm (red light) and 756 nm (near-infrared) in calculating the vegetation indices, it was found curves of NDVI (normalized difference vegetation index), RVI (ratio vegetation index), SAVI (soil adjusted vegetation index), and DVI (difference vegetation index) were bell-shaped after transplanting. Difference in vegetation index between two crops was due mainly to the growth rate of rice plants. When normalization with unit time, however, changes of NDVI were similar in both crops. Reflectance in the nearinfrared (for example, 756 nm) was suitable for estimating LAI (leaf area index), and their relationship was properly fitted to the inverse of the Mitscherlich function. |
本系統中英文摘要資訊取自各篇刊載內容。