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文中基于高光谱与田间试验进行了甜菜不同生育时期(甜菜幼苗期、叶丛生长期、块根膨大期和糖分积累期)SPAD值估测研究。采用便携式ASD光谱仪和SPAD-502叶绿素仪分别实测了甜菜冠层反射光谱和SPAD值,分析不同生育时期冠层高光谱响应特征,并对12种光谱指数与不同生育时期的冠层SPAD值进行相关性分析,最后建立了SPAD值的最佳估测模型。研究结果表明:在可见光波段(450-680nm)与近红外波段(760-950nm),甜菜不同生育时期冠层反射光谱存在明显差异;不同生育时期所筛选的3种光谱指数与SPAD值均达到了极显著(p<0.01)或显著(p<0.05)相关水平;甜菜幼苗期、叶丛生长期、块根膨大期和糖分积累期分别以NDVI、SDr/SDy、CCI和SDb为单一自变量所建立的估测模型最佳,模型决定系数R~2分别达到了0.573、0.212、0.363和0.324。
In this paper, based on hyperspectral and field experiments, the SPAD values of sugarbeet at different growth stages (sugar beet seedling, leaf growth, tuberous expansion and sugar accumulation) were studied. The canopy spectral reflectance and SPAD values were measured by portable ASD spectrometer and SPAD-502 chlorophyll meter. The canopy hyperspectral response characteristics at different growth stages were analyzed. The correlations of 12 spectral indices with canopy SPAD values at different growth stages Finally, the best estimation model of SPAD value is established. The results showed that the canopy reflectance spectra of beet at different growth stages were significantly different in the visible light (450-680nm) and near infrared (760-950nm) bands. The three spectral indices and the SPAD values of the three beet (P <0.01) or significant (p <0.05) correlations; NDVI, SDr / SDy, CCI and SDb were established as single independent variables in the stages of sugar beet seedling growth, leaf growth, tuberous expansion and sugar accumulation The estimation model is the best, and the coefficient of model determination R ~ 2 is 0.573, 0.212, 0.363 and 0.324 respectively.