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在2010与2011年度冬小麦生长季通过大田小区试验,利用ASD便携式野外光谱仪和SPAD-502叶绿素计实测冬小麦冠层的高光谱反射率与SPAD值.分析不同SPAD值下的冬小麦冠层光谱特征,建立了基于归一化植被指数(NDVI)与比值植被指数(RVI)、小波能量系数的不同生育期冬小麦SPAD估算模型.结果表明:随着SPAD值的增大,“绿峰”与“红谷”特征愈加明显.在冬小麦返青期、拔节期、抽穗期、灌浆期NDVI估算SPAD的效果较好,估算模型的R2分别为0.7957、0.8096、0.7557、0.5033.小波能量系数回归模型可以提高冬小麦SPAD的估算精度,在返青期、拔节期、抽穗期、灌浆期以高频、低频小波能量系数为自变量的冬小麦SPAD估算模型的R2分别达到0.9168、0.9154、0.8802、0.9087.
The hyperspectral reflectance and SPAD values of winter wheat canopy were measured by ASD portable field spectrometer and SPAD-502 chlorophyll meter in field trials of winter wheat in 2010 and 2011. The canopy spectral characteristics of winter wheat at different SPAD values were analyzed and established Based on normalized vegetation index (NDVI) and ratio of vegetation index (RVI), wavelet energy coefficient of different growth stages of winter wheat SPAD estimation model.The results show that: with the SPAD value increases, “green peak ” and “ Red Valley ”is more obvious.When NDVI of jointing, jointing, heading and filling stage of winter wheat, the effect of SPAD is better, R2 of estimation model is 0.7957,0.8096,0.7557,0.5033, respectively.Wavelet energy coefficient regression model can be improved The estimation accuracy of winter wheat SPAD was R2 = 0.9168,0.9154,0.8802,0.9087, respectively in spring wheat SPAD estimation model at returning green stage, jointing stage, heading stage and filling stage with high frequency, low frequency wavelet energy coefficient as independent variable.