中文摘要：

2006年4^8月，通过大田试验，测定了7个密度梯度下3个品种的春小麦冠层、叶片在不同生育期的高光谱反射率。结果表明：孕穗期，不同密度的春小麦冠层和叶片光谱差异明显，波形相似，其冠层光谱反射率在可见光区随密度增大降低，在近红外区反射率随密度增加升高；乳熟期，不同种植密度春小麦冠层光谱在可见光区的差异比近红外区小；不同密度的叶片光谱在可见光区和近红外区的变化在不同生育期表现出一致性，但随密度变化的规律性不明显；不同生育期的冠层光谱表现为乳熟期的反射率高于孕穗期；叶片光谱表现为乳熟期较孕穗期在近红外光区反射率大大降低；不同品种春小麦的冠层和叶片光谱存在一定差异；孕穗期，不同品种的冠层光谱在可见光区差异较小，差别主要表现在短波红外和近红外区；成熟期，不同品种冠层光谱的差异小；不同品种叶片光谱在近红外区的差异显著；春小麦红边存在双峰现象，从孕穗期到乳熟期，红边位置蓝移，红边幅值降低，红边面积减小：红边幅值的变化可用于估产，红边位置的变动可指示生育阶段。

英文摘要：

The canopy and leaf hyperspectral reflectance of three spring wheat cultivars at their different growth stages and with seven planting densities were measured in field during April and August 2006. It was found that at booting stage, the canopy and leaf reflectance of spring wheat under the 7 planting densities was distinctly different, though the wave shapes were similar. Meanwhile, the canopy spectral reflectance decreased with increasing planting density in visible （VIS） region but increased in near infrared （NIR） region at booting stage, while this change was not evident and the difference in VIS region was less than that in NIR region at ripening stage. The change of leaf reflectance under different planting densities showed coherence in VIS and NIR regions at different growth stages, but the change with planting density was not clear. The canopy reflectance was higher at ripening than at booting stage; while the leaf reflectance in NIR region was higher at booting than at ripening stage. There were some differences for different spring wheat cultivars at canopy and leaf level. At booting stage, the difference of canopy spec-tral reflectance among different cultivars was less in VIS region but obvious in NIR and shortwave infrared regions, while the difference at ripening stage was less. The difference of leaf spectral reflectance among different cultivars was obvious in NIR region. There existed ＂double peak＂ phenomena for the spring wheat at vegetative growth stage. Additionally, there existed a ＇ blue shift＇ phenomenon for the position of red edge （ λred）, and the slope of red edge （Dλred） and the area of red edge （Sred） at canopy- and leaf level were decreased from booting to ripening stage, suggesting that the ）Lr~d change could be used to estimate wheat yield, and Sred could be the indicator of wheat growth stage.