施用氮肥對水稻植株氮素、葉綠素及植被反射光譜之影響

Changes of Nitrogen and Chlorophyll Contents and Reflectance Spectral Characteristics to the Application of Nitrogen Fertilizer in Rice Plants

李裕娟(Yuh-Jyuan Lee) ； 楊純明(Chwen-Ming Yang) ； 張愛華(Ay-Hwa Chang)

《中華農業研究》 51卷1期 (2002/03) Pp. 1-14

https://doi.org/10.29951/JARC.200203.0001

摘要

本文研究係在行政院農業委員會農業試驗所農場（臺中縣霧峰鄉）進行，以水稻臺農67號品種(Oryza sativa L. cv. TNG67)為試驗材料，施用氮肥為對照田區，不施氮肥為處理田區，探討施用氮肥對水稻植株與葉片之氮素、葉綠素及植被反射光譜(350~1100mm)之影響。田間試驗實施於1999年一、二期稻作生育期間，同時測定土壤氮素及稻株的生長性狀、葉片氮素與葉綠素、地上部氮素與葉綠素、及植被反射光譜。根據試驗結果，施用氮肥田區之土壤氮素普遍高於不施氮肥田區者，使得生長其上的稻株氮素與葉綠素含量有高於不施氮肥田區稻株之趨勢。由全生育期的葉片及地上部植體葉綠素與氮素含量變化，顯示一、二期稻作的施肥田區植株普遍高於不施肥田區植株，且氮素含量與葉綠素含量之間具有顯著曲線相關。無論一、二期稻作，施肥區稻株的葉面積、地上部鮮重及植株高度均優於不施肥區稻株，惟二期稻作之差距不若一期稻作明顯。兩期作在幼穗分化期至抽穗期量測之植被反射光譜曲線，以近紅外光波段(740-1100nm)較能反映出施用氮肥的效應，可作為區分施用氮肥與否之指標波段。續以波長反射比與葉片氮素含量進行相關強度分析，發現藍光波段及近紅外光段的相關係數絕對值較高。在量測之光譜範圍中(350-1100nm)，一期稻作以720nm位置相關係數最高，二期稻作則以708nm位置最高，此兩波長之反射比與葉片氮素之關係呈現二次曲線函數，決定係數(R^2)分別達0.856（一期作）及0.550（二期作），可利用於氮素估測與追蹤。又由反射光譜曲線之綠光波段反射比(G)、紅光波段反射比(R)及近紅外光反射比(NIR)之波段比G/R、NIR/R、NIR/G與NDVI（標準差植被指數）在水稻全生育時期的分佈，發現亦呈現二次曲線趨勢，曲線高峰出現在穗形成期，而施用氮肥田區之測值在全生育時期皆高於不施肥田區者。此一現象類似於稻株葉片及地上部之氮素與葉綠素含量表現，並顯示稻株植體葉綠素含量較多者，多處於較高氮素含量狀態。綜合上述結果，顯見施用氮肥田區的稻株之氮素、葉綠素及生長性狀皆高於不施肥田區之稻株，在植被反射光譜上的區分，以幼穗分化至抽穗期間之穗形成期近紅外光波段分辨施肥與否較佳，波段比NIR/G及NIR/R亦適合利用於區分施用氮肥效應。

關鍵字

水稻 ； 氮素 ； 葉綠素 ； 光譜特徵 ； 波段比 ； 植被指數

並列摘要

Field experiments were conducted in the experimental farm of Taiwan Agricultural Research Institute, Wufeng, to study changes of nitrogen and chlorophyll contents and spectral characteristics to the application of nitrogen fertilizer in rice plants (Oryza sativa L. cv. TNG67) grown in the first and the second cropping seasons of 1999. It was shown a higher level of soil nitrogen in the soil applied with nitrogen fertilizer. Nitrogen and chlorophyll contents in leaves and aboveground plant parts of rice from the fertilized plots were greater than that in the plants from the non-fertilized plots during both growing seasons. Nitrogen and chlorophyll were shown curvilinearly correlated. Plants supplied with fertilizer had higher leaf area, aboveground fresh weight and plant height, especially in the first crop. Reflectance spectrum of rice canopy was affected by the application of nitrogen fertilizer with the distinct differences in the near-infrared waveband (740-1100 nm) from panicle initiation to heading stage in particular. By the correlation intensity analysis, it indicated that reflectance in blue and near-infrared wavebands were closely correlated to leaf nitrogen content. The highest correlation coefficient was located at 720 nm and 708 nm for the first and the second crops, respectively. The relationship between reflectance and leaf nitrogen at these two wavelengths was best fitted to the curvilinear function, with the determining factors (R^2) of 0.856 (First crop) and 0.550 (Second crop), respectively. The waveband ratios of G/R, NIR/R, NIR/G, and NDVI (normalized difference vegetation index) were curvilinearly distributed during rice growth in both crops with the plateau in the panicle formation stage. The ratios were found higher from the fertilized plants, with NIR/G and NIR/R as better indicators.

並列關鍵字

Rice ； Nitrogen ； Chlorophyll ； Spectral characteristics ； Waveband ratio ； Vegetation index