陇中黄土高原春小麦光谱反射特征

Spectral reflectance characteristics of spring wheat on Longzhong Loess Plateau

通过田间小区试验,测定了3个春小麦品种(高原602、陇春8139和定西24)在不同生育期和不同种植密度的光谱反射率及对应叶面积指数(LAI)和地上生物量,分析了其光谱反射的一般特征和红边参数特征以及光谱变量与LAI和地上生物量的相关性。结果表明:在整个波段内,春小麦冠层光谱表现为高原602>陇春8139>定西24,其叶片光谱表现为定西24>陇春8139>高原602;春小麦冠层光谱在可见光波段和中红外波段成熟期明显大于孕穗期,而叶片光谱在近红外波段孕穗期明显大于成熟期;随着种植密度的提高,在近红外波段冠层和叶片的光谱反射率逐渐增加;冠层光谱的红边均具有"双峰"现象,从孕穗期到成熟期,冠层红边位置呈现"蓝移"现象;LAI和地上生物量与冠层光谱变量之间存在较好的相关性。

In a field experiment, the spectral reflectance, leaf area index （LAI）, and aboveground biomass of spring wheat varieties Gaoyuan 602, Longchun 8139 and Dingxi 24 with different planting densities were measured at their different growth stages, and the correlations among the test parameters were analyzed. The results showed that within the range of test wave bands, the maximum value of canopy spectral reflectance was the highest for Gaoyuan 602 and the lowest for Dingxi 24, and the maximum value of leaf spectral reflectance was the highest for Dingxi 24 and the lowest for Gaoyuan 602. The canopy spectral reflectance in visible and mid- infrared wave bands at maturing stage was obviously higher than that at booting Stage, while the leaf spectral reflectance in near infrared wave band at booting stage was obviously higher than that at maturing stage. The canopy and leaf spectral reflectance in near infrared wave band increased with increasing planting densities. For the three varieties, there existed ＂double peak＂ phenomenon at the red edge of canopy spectra; and from booting to maturing stage, a ＂blue shift＂ phenomenon occurred at the red edge. The LAI and aboveground biomass were better correlated to the canopy spectral variables.